For those outside the hobby, the majority of objective measurement/science-based audiophiles generally agree on a few things re: amplifiers.
1. In an average room one solid-state amplifier (Class AB or Class D or other "switching" amps) will sound indistinguishable from another, assuming you're not driving them to distortion. (Less powerful amps will distort at lower levels of output) Long story short, these amps give you more of an objectively correct reproduction of the input signal.
2. All bets are off when it comes to vacuum tube amps. A lot of them add various distortions that may or may not sound pleasing to various folks. You can think of them as the aural equivalent of Instagram filters that make things more pleasing at the expense of absolute accuracy to the source material.
3. The subtle sonic differences between amplifiers are dwarfed by the distortions induced by speakers and the room itself.
Which is "better"? Tube or solid-state?
Well, there's nothing wrong playing with tubes and seasoning your listening experience with various euphonic distortions. Ultimately, it's all about enjoying your sound!
As a practical matter, solid state amps are more economical generally going to give you the most enjoyable results through the widest variety of material. Imagine messing around with the color settings on your TV and putting them into a slightly bizarre state. Some things are going to look amazing... and a whole lot of stuff is just going to look weird. So in general you'll get the most enjoyment just by staying accurate.
That transfer function argument is within an ace of saying all amplifiers sound alike, and it's shaky. OTOH we have ABX data that cannot disprove the proposition. However, only one transfer function admits of that possibility even according to Carver (well, indirectly via Stereophile) [1]).
Audiophilia is wonderful because it is full of set-piece arguments that promote the drinking of lots of Scotch.
In my view, nobody's saying that all amplifiers sound alike. Indeed, you can design an amplifier to have a pronounced sonic signature, which is common in the guitar amplifier world.
A more precise statement might be that two amplifiers with the same transfer function should sound alike, but this needs additional clarification, namely a specified margin of error. Finding out that margin of error has been a pursuit of acoustics research, and is the original motivation for the ABX test. For instance, I read that when Sony developed their MiniDisc recorder, the data compression scheme was subjected to extensive ABX testing.
-I don't think 'all amplifiers sound alike' is a widespread opinion, but rather (in engineering circles, at any rate) that any competently designed amplifier, run within its limits, sound like any other competently designed amplifier run within its limits.
Audio amplifiers are pretty much a solved problem, to the extent that in order to create a 'house sound' or whatever the preferred audiophile term is nowadays, the manufacturer needs to introduce distortion to differentiate their product from the others. Sigh.
(The above obviously only applies to amplifiers intended for faithful reproduction; guitar amps and the like is a whole different beast - where distortion serves a valid artistic/creative purpose!)
Indeed, and this can be a problem with "audiophile" gear that is sometimes built with exceptional craftsmanship but not necessarily designed with the best electrical performance in a mainstream sense. For instance if someone believes they must experience a feedback-free Class-A amplifier, well, yes they're going to have some thermal drift and poor power supply noise rejection. that can be hard to replicate. ;-)
Good mainstream designs take component tolerances into account, and it's worth remembering that a 1% variation is a tiny fraction of a dB.
It's a joke, understand. Carver demonstrated that he could build a transistor amplifier that matched the transfer function of an arbitrary tube amplifier. It didn't sell and annoyed the tube fans. So he built this thing to shut up the extreme audiophiles. It still sells.
I worked on a pair of these amps, had bias problems. Wow they were annoying. Really nice for impressing your friends, or heating up your listening room, or making your electric meter spin, if you are into that. I was not impressed. I felt a modified Dynaco ST70 was way more listenable. The output transformers were really not rated for full bandwidth at full power. Circuit was not very nicely done. I would give it a solid "meh" on my audio scale. You can do a lot better for a lot less.
Sweet Jesus, a 40 watt tube amplifier with just one pair of kt88s cranked all the way up will just about make your eardrums explode. I can’t even imagine what madness led this lunatic to put 18 of them in each channel!
1. In an average room one solid-state amplifier (Class AB or Class D or other "switching" amps) will sound indistinguishable from another, assuming you're not driving them to distortion. (Less powerful amps will distort at lower levels of output) Long story short, these amps give you more of an objectively correct reproduction of the input signal.
2. All bets are off when it comes to vacuum tube amps. A lot of them add various distortions that may or may not sound pleasing to various folks. You can think of them as the aural equivalent of Instagram filters that make things more pleasing at the expense of absolute accuracy to the source material.
3. The subtle sonic differences between amplifiers are dwarfed by the distortions induced by speakers and the room itself.
Which is "better"? Tube or solid-state?
Well, there's nothing wrong playing with tubes and seasoning your listening experience with various euphonic distortions. Ultimately, it's all about enjoying your sound!
As a practical matter, solid state amps are more economical generally going to give you the most enjoyable results through the widest variety of material. Imagine messing around with the color settings on your TV and putting them into a slightly bizarre state. Some things are going to look amazing... and a whole lot of stuff is just going to look weird. So in general you'll get the most enjoyment just by staying accurate.