To the previous article in this series
Introduction
After the brief – and not exhaustive – overview of amplification classes, first article of this series can be found here, the next step would have been to make considerations about the overall quality of an amplifier.
A rough summary of the previous article could be: "what is advertised doesn’t matter – including the amplification class – because the quality of an amplifier is defined only by its real characteristics".
At this point the reader could rightfully expect a description of these characteristics, how to recognize them and how they determine the behavior of the device and of other elements related to it.
A description that is not too technical, otherwise the only ones who could understand it would be those who already know the subject. And this is already very difficult for the one who is writing.
As many audiophiles know, the Hi-Fi sector is pervaded by a series of clichés, prejudices, beliefs and mysticisms – yes, even mysticisms – not only on technical characteristics, but first of all on the philosophy of life itself.
Because the way a person sees things in general, then reflects itself on the details, every detail, from the type of recording to the cladding of the listening room.
Anyone who has even attempted to make a serious speech in this field - and in others - has certainly clashed with absolutist, denialist, dogmatic positions.
Or with attitudes such as "yes, of course, all these technical things are there, but anyway in the end everyone decides based on how they feel at that moment", and I don’t know which one is worse.
Not to mention the aggressive attitude – perhaps this one is the worst - of those who reject any rationalization from the start, and attack technique and technicians as if they were the "destroyers of poetry of the audio system" and not those who instead designed and built that system.
Science outreach in these conditions is not difficult, it’s impossible. And very depressing.
So, not to make yet another useless article on the subject – and there are far too many of them – we need to take more than one step back and set things the right way.
Arm yourselves with patience and good will, if you have any, because things will get interesting, I hope, and serious...
Does our audio system really exist?
There is a current of thought stating that reality does not exist, that it is only a creation of our mind. The idea is fascinating, so much that Einstein used the expression "is the Moon there when no one is looking at it?”.
Although to some people this question may seem absurd, doubting the existence of an objective reality that does not derive from us is an important position that deserves respect and consideration. And, no, we’re not talking about quantum physics or relativity: phrases like "reality depends on the observer" or "everything is relative" are wrong conclusions of those who have never really seen and understood those theories. Too bad that professional scientists don’t clearly explain that neither the quantum model nor the relativistic one leave such a power to the observer, especially not a subjective power.
Nevertheless, the question on objective reality remains.
This question emerged thousands of years ago with philosophy, that still hasn’t come up with an answer, and so I would like to suggest a small experiment to get your own idea on the subject in a direct, personal, sensitive way, to eliminate or at least minimize the doubt.
Go to a place you do not know, the home of someone you have never visited, or maybe a hotel. Before opening the door, blindfold yourself, or avoid turning on the lights if it is dark outside. Open the door and move forward.
Here – we decline any responsibility – two things can happen:
- If reality is created by you, you will float in the void without bumping into anything, because nothing can be there since there is nothing you know about that place. If you might happen to visualize holes or wells, just think of a pair of wings to get out without any problems.
- If, on the other hand, reality exists - some reality, which may not be the only one but is "our" reality - then you will hit an object, a wall, a person. Something that others will swear was there even before your arrival. Which then confirms that this is a reality not created by you. And not only yours but shared with others.
A variant – not recommended – of the experiment to determine whether there is an objective reality is to run through the street with your eyes closed. If reality does not exist, we will pass through walls. The gentleman we see here opened his eyes too soon.
For all those who will float in the void: it will no longer be necessary to read or talk about amplifiers, because you can imagine – and thus create from nothing – a symphony orchestra, or even play directly with your favorite artist, who cannot refuse since it’s your creation. In this case we say goodbye right now, thank you for your time and for having created me so far. Please, next time imagine me rich, thank you.
For those who will not float in the vacuum: if you are still interested in amplifiers, after a brief check-up with the orthopedist you can come back and read here. We’ll understand each other.
There is also a third possibility, of course, which I mention only now because it is a variant of the second: that reality is created entirely by a superior being, which is also an absolutely respectable position. In this last case, remember that electrons, valves, transistors, equations, measuring instruments and even technicians and designers have been created for the same reason - whatever it may be.
So, you cannot ignore them otherwise you’ll disrespect he who created them for you.
Let’s talk about words
Words were born to convey information, from declarations of love to weather forecasts, and are a useful and wise tool, as long as they are used for their original purpose: to describe facts, moods, reasoning, thoughts.
Sharing feelings is vital. Telling a story that happened is important. Describing a reasoning is useful and often generates other equally useful reasonings.
Instead, words not related to something are obviously meaningless, so that until a few years ago they were attributed only to those who had mental problems. Before the Internet.
Today, unfortunately, most of the words said and written are "unrelated". And this is bad. We have "opinions" that we cannot explain or link to real facts or reasoning. We say things about topics or events that we do not know. We do not ask for information; we do not provide information. All this is the very denial of words. And, no, it is not true that on a subjective level it is justified. It is not true at all.
Screaming monkeys at the sides of a puddle, from the film 2001: A Space Odyssey
To watch the same scene, you don't need to look for a 1968 movie, you just need to take a look at any social network or TV talk show.
Even on a subjective level, a statement is valid only if it comes from our experience or our articulated thinking, otherwise it’s air that comes out of the wrong side. I couldn't say "Jerry has stolen" without knowing the facts - and possibly the way to prove them - and even the phrase "in my opinion Jerry has stolen" in the absence of any feedback is not an opinion but a slander. And for this it is punishable by law. But too few are punished.
I can say "I have the impression that I can't trust Annie" because it's a subjective thing, it concerns only me and doesn't offend anyone. Instead, when I say "the Earth is flat" I say something objective that concerns everyone. So, if I do not demonstrate in an equally objective way that the Earth is flat, I have not expressed an opinion, but nonsense.
If I and another person have different opinions but the other person has proof, real evidence, verifiable testimonies, while I have only my "idea", then it is not true that my word is as good as his. So, for the same reason, it does not deserve the same respect.
There is no "politically correct" equality between facts and words: facts always win
Anyone who says that everything is "opinion to be respected" is immediately in conflict with his own conviction: try to make him respect the opinion that his house, his money or his car are instead your property and you will immediately discover that they’re the ones who in the first place do not believe in all this "freedom of thought". So, this is also nonsense.
Freedom and creativity - which we are not dealing with here, but invite you to look up their true meaning, possibly in a dictionary - are much more than an excuse to justify nonsense, as ignorant people do.
Even those who consider themselves "outside the rules" can say so because matter behaves according to precise rules, otherwise their hearts would not beat and they could not breathe, listen, think nor complain. None of them would be alive if physics didn't work the same way for everyone. Thus, the "rejection of rules" is a rejection of life itself. Anarchists are subject to the Law of Gravity and all other laws, including the psychological and social ones that determine human behavior: they need them like everyone else, they are made of rules as well.
Thought “free of facts” is called lying, or insanity, or stupidity.
This bad habit of "disconnected words" leads us not only to contaminate the world we live in – because spreading nonsense does damage – but it gets us used to believing the "disconnected words" of others: it therefore makes us manipulable and weak.
Since we are no longer used to giving explanations for our claims, we have stopped asking for them. We complain about politics, about broken promises, but who among us is informed about what politicians are, have done in the past, and tell us today? We give power to people and ideologies we don't know; we buy objects whose content we have no idea about. Not seeking objective information about objects is really absurd.
Tim says "this amplifier sucks" but few ask him why, how he performed the tests. The "word" spreads, everyone repeats the "disconnected words", maybe someone replies that Tim doesn’t understand anything, but even his words are disconnected, because they do not discuss the merits of the matter. Result: unnecessary and damaging chaos.
Asking for explanations instead is fundamental, because we can understand:
- that Tim has never met, let alone listened to, that amplifier and therefore his statement is to be ignored
- that Tim tested the amplifier in an inappropriate room or with the wrong speakers, thus his judgment is incorrect and perhaps we will want to try and test out the amplifier ourselves with the right speakers in an appropriate room
- that Tim has conducted testing in a dishonest way, because he has an interest in making that brand or model look bad, so he is not reliable
- that Tim has actually carried out serious and verifiable tests, in the correct way and in the right environment, so the device really is of poor quality
As is evident, the sole fact of asking for explanations – that is, wanting to know the connection between words and facts or reasoning – makes those words useful: to evaluate the goodness of the statement, or to evaluate the credibility of the person making it. Knowing the details of the test, if there was one, can teach us something we don't know about how to evaluate amplifiers, moreover, to exchange this information we will be "forced" to discuss with Tim and the discussion could bring interesting insights to think about.
If this all seems obvious to you, ask yourselves, "Am I able to prove every statement I make? Am I able to explain the things I say, in order to convince someone who is asking me questions?" Because that's how it should be; otherwise we should refrain, keep silent.
Einstein said, "if you can't explain it, then you didn’t understand it".
All who are very familiar with a given subject complain about how much nonsense is uttered on the topic by those who are not experts. Similarly, before talking about things we have no experience with, we should ask ourselves if we too are going to spout out what others will recognize as nonsense. This would not make us infallible, but it would certainly make us better.
And, no, having attended the so-called "University of Life" doesn't really make us competent in fields where you need to put together a lot of knowledge and procedures derived from the work of hundreds of people over decades or centuries. Those who invest money and years of their lives to study complicated things instead of going out and having fun are not all fools. Instead, they are usually the ones who literally "build and maintain" the world.
Someone who does a certain thing for a living is usually much more reliable, because if he is paid then someone will expect results, i.e. facts that confirm his ideas and words. Essentially, his content will be selected, unlike what happens on the web or in a bar.
If you consider yourselves "experts" and have never had to ask for money in return for your contributions, you may be in error and not even be aware of it because your "knowledge" has never been put to the test. You might even do some damage.
Some professions demand that every word, every idea, must then be explained, proven, verified. And, if you say or think something false, there are consequences, for example you don't get paid or, worse, someone dies: think of doctors. So, those practicing these jobs have the habit of being very careful about what they say and thinking carefully about what they do.
A habit we should all have, because it would save the world and ourselves so much trouble. Then, of course, a doctor can make mistakes. But this does not entitle us to think that we are on his same level, because the worst of the surgeons may fail one operation out of two and would soon be fired, but the best of the journalists who criticize him would fail one hundred out of a hundred. The faults of others do not make us better; the only way to improve is to strive to learn the things we don't know.
We should be wary of people who despise things they don't know. Many people begin their sentences with "I don't understand anything about these things" and end with "that thing is no good anyway".
Such statement is not an opinion: it is just a parody of the tale of the fox and the grapes that it could not reach and therefore "were not good". If we are not competent, we should ask those who are.
Science is humanity
We live in strange times, where an odd and dangerous incoherence animates words and actions.
We criticize science or technology without knowing what they are. We complain about them and go so far as to blame them for our unhappiness. But we do it by posting a message online from our digital account. Or we curse modern foods because they are not produced in a "natural" way and then we go to get natural food from the farmer, but with our car.
If we were to be coherent - but as we have seen we are no longer used to it – the moment we complain about science or technology we should give up all comforts and securities, get rid of phones, computers and all other devices and go on foot, because even a horse-drawn carriage is an expression of technology, as are the clothes we wear, the houses where we live – even if made of wood or mud – the food we eat and the copper pot our grandmother used as a child.
Some technological items. Those who reject technology are invited to stay naked, go on foot, eat off the ground, wash in pools of water, and never comb their hair.
It's so hard for us to be coherent because the names we give things mislead us, far more than amplifier classes.
Do we know what science and technology are? Would we know how to explain it to someone?
After the release of the first part of this article, some colleagues called to tell me, amazed, that they did not know class-D amplifiers were analog and not digital. And this despite the fact that they had access to schematics and instrumentation, without ever seeing a bit in the final stage or a "step" in the output waveform.
Yet, these are people working in the field, and with excellent results. The point is that they had never really thought about the term "digital" and had taken commonplaces for granted. But "clichés" are often false, when they are not based on facts.
We're all a little bit like that. And it's not good for us, it makes us weak, fickle and sometimes desperate. Because if we give different names to things that are basically the same, like "digital" amplifiers as opposed to "analog" ones, then we will find ourselves in a messy situation because problems that do not exist will be generated.
Solving a problem that doesn't exist is impossible and therefore quite frustrating.
We create distinctions where there are none. It’s natural for us to do so. It happens because the most fragile need "enemies" to pick on in order to give meanings to things. But this is not a good way to live. At best it distracts us from the real issues, such as disease, pollution, overpopulation and other issues where focus and competence are needed, not anger or frustration. I don't know how many of you would let an angry worker treat you rather than a capable, calm doctor. None, I would say.
It is difficult to talk about amplifiers - and many other things - with those who criticize science and don't realize they are scientists as well. Because we all are: every time we do something in an organized way, taking into account past experiences, and we do it with a model, a method in mind, well... that's science. When someone strives in the kitchen, having a recipe in mind and practicing to improve it, that's science.
Not in a manner of speaking, not in a broad sense: it's really science.
A scientist at work with the help of technology.
In a nutshell: any activity that is aimed at knowledge and its application to know more – of any subject, even theology – that is science.
When, on the other hand, knowledge is used not to produce more knowledge but for practical applications, it is called technology.
Technique is a special case of technology that concerns only one subject.
It goes without saying that almost all constructive and useful works have something to do with science or technology.
The farrier who shores a horse produces technology and the farmer who takes care of a plantation is a scientist and engineer. Plantations do not exist in Nature, man invented them after studying the life cycles of plants.
The listening tests we do to understand if our audio system performs better with jazz or rock songs are science. We produce technology when we build a loudspeaker or a cabinet to put our turntable on.
Although we are not "doctors" we are scientists, all of us, in some way. What distinguishes a "professional" scientist from a human being is not the academic title but the fact of putting much effort into his/her science by following the scientific method, which is a set of "game rules".
Rules that are effective, humble – humility is at the basis of science – and common sense.
Think about the difference between a group of kids playing with a ball – having fun as it is – and major league players playing in a championship.
The difference, apart from the performance of those who have practiced more, is that the professional must follow some common rules, because otherwise the game would be messy and unfair, in fact those who do not follow the rules are expelled.
In science, the "game" is to understand things in a structured and orderly way, so that we can convey them to everyone, and avoid mistakes as much as possible. That's what the scientific method is for.
When someone's work is disavowed by "official science" it's not because they said "something uncomfortable that annoyed the powers that be" but because the research has not been carried out properly. Rules never enter into the merits, only the manner.
Art differs from science in the lack of rules and in the fact that its purpose is not so much understanding as it is expression. But don't think the two fields as separate, they're not at all: art and science are connected by technology, the creation of "tools" to make... anything.
Even the most "hard-core" artist uses technology: as does the musician with his violin – in fact the luthier who built it is a sound scientist and a wood engineer – and the painter with his brush and colors, because to produce them it required first the science of color and then the technology of bristles. To find a human activity where science or technology do not enter, we must confine ourselves to the domain of instincts.
Almost everything that allows us to express art and feelings is technological.
If we tried for a moment to look outside of our species, we would immediately notice that everything else, from singing to sculpture, from procreation to murder, from swimming to flying, from fighting to raising a family, in Nature was present before us, in such a great variety of animals and plants that we still cannot classify them all.
So, on these activities we have not brought anything new under the Sun.
Not even feelings and desires are exclusive to humans: for example, a dog loves and wants to be loved. Mine is also jealous and in love with the cat.
What's left? The thing that above all distinguishes humans from other living beings: constructive thinking, the ability to imagine one thing and connect it to others. And maybe get something useful out of it for our everyday lives.
In two words: science and technology.
Since prehistoric times, before philosophy and religion, when we were still expressing ourselves with grunts, engineering was born: the sharp stones we used to hunt with were already tools.
So, these things that some see as incomprehensible and evil entities, covered by a dark cloak, spreading death and misery, are really... just us.
If they take this away from us, we're back to being beasts like the others. And not even among the most interesting or beautiful.
The meaning of "science" is nothing more than the natural inclination of human beings to clear the ground from chaos and bring some order and awareness, like when snatch a few feet from the desert and turn it into a cultivated garden. Those who see something bad in this, keep in mind that they are looking at themselves and their fellow humans.
It is necessary to remember that, behind every bomb that is thrown, besides a scientist who thought it up and an engineer who built it, there is a person of power who gave the order to launch it and, behind that, there are people who elected that person and share their hatred for the target. Science and technology are just words, they don't kill.
Too often we give those words the responsibility that instead belongs to our humanity: becoming aware of this means understanding that the use of technology is governed exclusively by our human desires and instincts. Science does not "tell" you what to write on Facebook, which people to help, or discriminate against, or despise. It doesn't "tell" you to pollute or throw bombs, on the contrary, it warns about the consequences, if you have the brains to understand them. It is us, and us alone, who decide what to destroy, including ourselves.
If you use the Internet to insult or to play games instead of informing yourself and grow, it's only your choice, and it takes little to understand that it's a choice driven by instincts and not by equations.
Do we want a better world? Let's work on our humanity, on education and culture.
To use a metaphor, science and technology allow us to have a more powerful car that can carry more people, but the steering wheel is always in the hands of our "humanity", we are the ones who set the direction. Anyone who goes in the wrong direction and blames the car is either irresponsible or stupid. Above all, if we blame the car instead of the driver, we will not prevent future accidents, because the cause remains.
When an oil tanker gets damaged and pollutes the sea, the cause is rarely in the design, rather it is in the greed or stupidity of those who spared on safety. And the fuel that kills the environment is extracted to meet the needs of people and their children, and by those needs other people with desires and urges are enriched. Rather, we should choose better who makes the decisions. And ask us if our needs are the root of some problem, in which case there would be no point in complaining about it or blaming others.
"Accidents" involving "science and technology" almost always have their cause in human decisions, governed mostly by instincts and feelings.
Science therefore can neither be defended nor attacked, because it is only one of the words useful to describe the human race, no one excluded. A word that identifies us.
The reason why many people rail against this word is the lack of understanding of things – always our fault because we don't deepen our knowledge – which generates uncertainty and fear, because we humans replace the lack of information with negative information. If we don't hear from a friend, the first thing we think is that something bad has happened to him or that he is angry at us, not that he has won the lottery and is having a good time on the other side of the world. Ignorance breeds fear.
To overcome this fear, we don't have to – and we can't – know everything, of course, but knowing at least the basics about the world we belong to would be of great help and would make us live better in all fields, including art and feelings which are continuously under study.
Today we have the possibility gain all sorts of information, taking advantage of it is up to us, rather than fueling chatter.
In the past those who were unable or unwilling to know things became extinct.
The rest of us – that is, us, Homo Sapiens, not Homo Ignorantus – can instead listen to music, building comfortable environments where we can place audio systems.
And, speaking of audio systems, there's another important issue that needs to be defined before we can comfortably talk about amplification technology.
Quantity is quality
Another important cause of misunderstanding when talking about technical things – and not only – is the so-called opposition between quantity and quality. Certainly, the two concepts are different, but they are also intimately connected and not opposed – or even exclude one another – as someone claims.
First of all, without quantity there is no quality, because if you think that the quantity of money, or food, or affection, does not matter, try to zero it or divide it by a thousand.
If you lower your salary to a thousandth, the quality of your life will worsen, and I can guarantee that even among the supporters of the motto "quantity doesn't matter" receiving two-thirds of their salary would be a cause of great anger. We conclude that perhaps they haven't thought this through.
If they gave you food, great food, the best food you could find, in quantities of half a teaspoon a day, the quality of your life would plummet, because you would starve.
If we were to receive the most beautiful gesture of love, the most sublime, only once in our lives, the quality of the rest of our existence would be bad anyway, because we would live first in hope and then in regret of that one gesture.
The argument – definitely wrong – that is brought in many examples is of the type "it is better to have a 5W amplifier of good quality than a 100W one of bad quality", and it is incorrect because who brings it is avoiding to show that even 5W is a quantity.
Try a 0.01W amplifier of the best possible quality with your speakers: you won't hear anything. And 100W with a little distortion are better than nothing. So what happens to quality?
Of course, you have to determine at what value the power is too little, i.e. the amount below which quality no longer matters because you won't hear the differences. And, believe me, 5W is very close to that value, even for those with good hearing and high efficiency speakers. Later, we will see why.
If your car had a beautiful electric engine equipped with all the best solutions to consume and pollute very little, but this had a tenth of the power of the original, you could not get out of the parking lot.
And so, ultimately, the discussion is always and also quantitative. You can't talk about quality without also talking about quantity.
"Quality" relies on "quantity" in a physical world like ours.
This happens because our reality is made up of quantity, at every level. "Pure" quality does not exist. It would be, for those who have read the first part of the article, the information entering the amplifier, which as we have seen is not able to move the speakers.
Even that, however, has its own energy, different from zero, and if you take it to zero... the information disappears.
The statement "the thickness of the paper where you write is not important" is nonsense if we try to write with a pen on a paper that is one-thousandth of a millimeter thick, because the paper will tear to pieces and we won't be able to write anything.
The statement "the size of the pen is not important, but its quality is" is definitely false, if someone gives you a pen that writes very well but is 5 meters long and weighs a ton, because you won't be able to use it.
Everything is quantified, to be precise it must be quantified, if we want it to work.
The contrast and separation between quality and quantity is just some more nonsense that is spread around and unnecessarily complicates life.
The memory of a computer has dimensions, the data that travels in USB or network cables has currents, voltages, speeds – all quantitative characteristics – and we cannot ignore them, or rather we can but they will not ignore us.
Don't forget: quantity always matters. Always. Even for human matters, not just technical ones.
There are cases where quantity and quality even coincide. In many athletic disciplines, as well as in car rallies, the contenders are measured in individual tests – note the term "measure", which is purely quantitative – and the final ranking, i.e. the quality of the performance, is given exclusively by the quantitative comparison of a number, for example time or height or weight.
Provided nobody uses wings, therefore, the best rally team is the one that makes the lowest time on the track. Of course, interesting discussions can be made on how the driver sets the curves, on the way he manages the braking, on the elegance of the skids, but the quality of his performance corresponds to the quantity of time he takes to cover the same track as the others.
A weightlifter wins the Olympics regardless of the "quality" of the weight he lifts, whether it is iron with rust or not, painted well or with stains, whether instead of iron there is lead or aluminum. The quality of a weightlifter corresponds to the quantity of the weight he lifts.
Audiophile weightlifting, challenging Olympic test with no less than 4 stereo ways. A vacuum tube is also present, but not visible in the photo.
We find ourselves precisely in the case of an audio amplifier: what we call "quality" are quantitative characteristics: distortion, frequency response, resolution, control, spatiality and all the other parameters that "make up quality" are actually measurable quantities, just as power is. Because our ear perceives all and only quantifiable things, being a physical object. And this should not seem irreverent or despicable, it's just the way we are and we must acknowledge it.
Knowing that quality is as measurable as quantity should instead cheer us up, because it makes things much easier: since there is no opposition, it is certainly possible to obtain, for example, high power and high-quality amplifiers, without having to sacrifice anything. The important thing is to know what to look for.
What to do, then? Throw it all out and start over because someone wrote that the things we have been discussing about for years are nonsense?
No, certainly not. This second part of the article is intended to make those more intelligent reflect on the opportunity of considering different points of view from those we have been hearing for decades, and some thoughts can start from the things written here. Leaps sof faith are not asked for, golden rules are not handed out, but we try to point out the contradictions of certain "philosophies" and the advantage of considering things in a less conflicting and more connected way.
If an amplifier sounds better than another, according to you, buy it, and enjoy it.
But if you want to know the real reason why it gets along so well with your speakers, you'll have to ask a good technician, not your audiophile friend who doesn't know Ohm's law because he is a blacksmith, even if he has a lot of "experience".
Moreover, you should ask yourself why, after so many years spent investing time and money on high fidelity, your friend never bothered to know more about the "voltages and currents" matter that is really easy to understand, easier than the instructions of a washing machine. "Car enthusiasts" who have never opened an engine hood are not credible, because cars are more than just bodies and seats.
Don't settle. Above all, don't settle for opinions and advertisement.
The editor of this magazine could look at Hi-Fi "from the heights of his experience" of decades of audio frequentation, because he knows a great number of sources, speakers, amplifiers, cables, accessories, brands, designers and vendors. And who knows what else.
Instead he chooses to keep learning: he constantly asks what is behind the effects that his well-trained ear easily detects while the technician needs hours of measurements using expensive equipment.
Now, the true audiophile appreciates technical explanations, and the true technician will be happy to give a name and a face to the parameters that bring joy – like dynamics – or sorrow – like distortion – to those who pay and judge his work.
If you have read this far, you will have guessed that everything in this field has an explanation, maybe a simple one. And, if a technician is not able to explain to you what is the cause of that particular sound you are listening to, it is probably his limit, not yours.
Collaboration between those who design audio systems and those who use them can only improve things and clean the field from waste and frauds.
To draw your attention – without spoilering the arguments – in the next articles, for those of you who want to read them, we will treat and find the confirmation and explanation of the following phenomena:
- the human ear is a measuring instrument
- tube amps produce richer sound
- audio cables make a difference in listening
- some amplifiers work better with some speakers and worse with others
- power is a qualitative factor
- and other interesting things...
End of second part - To be continued...
