The age old question: besides the obvious aesthetic attractiveness, is there really any kind of objective advantages to tube-based audio amps as opposed to solid-state semiconductor based ones?
One important point though: when making guitar amps with newer technologies such as class D, we must redesign everything so that the amp -I mean the power module- will never clip; no matter what we throw at the amplifier main input, the power module must never be driven into distortion because class D distortion is plain awful. That requires a lot of redesign: no more clipping tubes, coils driven into saturation, purposely weak designed power supplies etc, but simply speaking we distort before and keep the level put in order not to distort after. This makes things even more interesting because one builds the guitar sound much before it gets to the final stages, the only further contribution to the sound being the speaker and the cabinet, not the amp module.
I fall in the camp that thinks we haven't fully figured out what conclusively decides subjective sound quality. It makes things much more interesting and open to more research to settle debates on solid state vs tube, sigma-delta vs r2r dacs, full range driver vs other speaker configurations, cables/interconnects/power-cords matter or not and things like that).
Some interesting links (I don't endorse what these guys are saying but find them VERY interesting):
About DACs: http://www.streamplayer.io/v1/sharing?v=8Mn5PrnZV-k
About whether audio power cables make a difference (Ask Paul from PS audio): http://www.streamplayer.io/v1/sharing?v=8QuToO9JUfw
I've listened to a friend's $10k setup. It was more like a live concert than listening to a regular stereo. Yes, it had a tube amplifier. If you remember anything about the audiophile's setup, what was the setup?
Think about it, the question can easily be answered by blind A/B testing using real listeners with varying aptitude for discerning any differences and the qualities.
Over the years people have tried and failed often to show much difference, when tests were done with proper controls and with scientific rigor.
To be fair I haven't read up on the subject recently so if there's anything current that shows otherwise I'd be glad to read a link to a paper from a credible source.
The key thing is the equipment owner's self-suggestion, vs. whatever adequately controlled blind testing would reveal.
I've done a small amount of audio restoration work, in which you're often trying to judge (e.g.) how much of a noise-removal process to apply. How much of that high-frequency content is just noise, or is there actually some of the original signal still lurking in there? Apply too much noise-removal and you'll take away some of that signal.
In doing this you frequently bump up against the question, "Can I actually hear a difference?" My rather sobering experience when I actually put it to the test was that I was way beyond the point of being unable to identify different treatments of the same audio, any more than could be explained by random chance, and yet I was still telling myself I could hear a difference.
Rigorous double blind a/b/c/d tests using real listeners has been performed, and the research has been published in peer reviewed journals since the 80's.
What has happened is that most of the audiophile community saw research as a threat to their revenue streams and actively FUD around it. And the audio engineering community has simply moved on.
Here is a talk that could be very informative. https://www.youtube.com/watch?v=zrpUDuUtxPM
His book is worth a read as well.
I said studies have been done that failed to show any difference, that's absolutely true.
I said I was open to hearing about recent papers published showing otherwise, yet you've provided zero links to a peer reviewed paper. You offer a Youtube video? If it's a video about research can we just skip to a direct link to the science? Citation please?
I said it's not necessary to know if current testing equipment can detect differences, to know if people can tell the difference. True.
Where are the rigorous double blind studies, with full disclosure, conducted with no conflicts of interest in funding or affiliation?
And of course I assume we want to stay on topic and look at research that isolate amplifiers for some tests, not conflate them with moving parts such as speakers.
However, there is definitely a difference in sound, however subtle to some, between most tube and solid state amplifiers when it comes to recording music, as musicians tend to try to draw out certain sounds that are a consequence of the design of the amplifier, whether by overdriving the input or exploiting analog flaws, etc.
Even when comparing just tube or solid state amps, there can be a lot of variance between them.
This doesn't really apply to consumer-grade amplifiers where the goal is perfect sound reproduction. A good tube amp and a good solid-state amp shouldn't sound different to an untrained ear. But amplifiers used in production often try to differentiate themselves in some way sonically.
It's a little bit like the tonewood debate in guitars, no one has been able to objectively prove it in electric guitars but some people swear by it.