What is a tube amp? Why do audiophiles like it “better” than a solid state amp?

Very different, and much more precise, engineering than the old bass cab I bought as a kid, which rolled on casters and seemingly had enough room inside for me to crawl into, and had time best described as “flabby.”

Distortion in a tube guitar amp is introduced in the preamp, the phase splitter (for push-pull designs), the power amp, the output transformer, and the speaker cone.

There's also some distortion introduced by amps with tube rectifiers, as high current draw causes B+ (plate/anode) voltage to drop and changes the transfer characteristics of the tubes.

This is why there's some disparagement of "master volume" tube amps that attenuate voltage before the power amp to get a distorted sound at lower volumes- they lose the phase splitter and power amp distortion. Whatever the electrical design, when amps aren't cranked, they lose speaker distortion. This is why physically small amps are popular in studios- they can be turned up to their own limits to get distortion without being as loud as stage amps.

"Hybrid" amps that use a tube preamp and a solid state power amp certainly have some tube distortion from the preamp, but because of circuit design differences and different tubes used in the power stage, it isn't identical to a full tube amp.

Not that it necessarily "needs" to be. Digital modeling amps are getting closer, perhaps even close "enough." Play equipment you like to play and get a sound that you like and the engineering details don't matter.

The perfect amp is a wire with gain, no matter the technology it uses.

This is the flip side of guitar nut arguments: people swear that they have to use their analog pedals using, as you did, qualitative adjectives like "harsh". But all they really mean is that they have a specific sound out of their rig that they can't find an audio software engineer to acceptably model for them. And to be fair: that's a valid point! Software engineering is expensive. But it's got nothing to do with the capabilities or behavior of the hardware.

It's very easy to convince yourself that something is helping. It's very common in audio production circles to have had the experience of working on, say, a snare track, tweaking EQ or whatever, and to convince yourself that you've improved it only to realise that the EQ is bypassed or you're on the wrong channel - basically you wiggle some knobs that make absolutely no difference to the sound but still hear a difference.

I'm pleased you've found something that you enjoy, as after all, that's the point - whether you chose something on sound quality terms or not is irrelevant (as you have already realised they sound basically identical). If it means you enjoy listening to music more, you've won!

But agreed on the audio. Hey, at least someone can make some money off something that's doing some better service for maintaining old technology than hawking gold-plated cables.

Some of this can be demonstrated though objective measurements, for instance bass extension into the sub-100 Hz range can be much better on audiophile equipment.

(Sony also makes some very high end headphones that few people are aware of)

With the electric guitar, the tube amp is part of the classic form of the instrument, as it was known for half a century, and first came to be played. It's the physical instrument present on most of the classic recordings and which older players learned to play with.

This quest for authenticity, or whatever you want to call it, is surely psychological, and often, in my opinion, a bit silly. Marketing often plays on it, for sinister marketing reasons, sure. Still, when it comes to pianos (or violins or trumpets or whatever), making and using period-accurate instruments, in the way they were made historically, and played historically, is both rather popular as a hobby/art, and also a serious academic field. Why would the electric guitar be exempted?