Why don’t tube amps sound like tubes anymore?

@jond. Yeah this is what singled ended amps do for me as well whether tube or ss.
If you get the opportunity listen to the Pass stuff. I believe his I25 integrated is s.e. First set of watts run A so it does not get too hot.
Also, there’s the French company "Valvet" that also gives this impression to me and that is also an ss unit.
Tough to find however.

Maybe it's the switch to solid state rectification in the power supplies.  The old amps that used tube rectification, chokes and less capacitance had more sag, which added more warmth to the sound.

Hello, I agree with you’re opinion about most of the tube amps made today. This is happening because designers know how to make tube amps sound more accurate than the designs yrs ago. Also, many parts like capacitors made today are cleaner and better sounding. Another factor is the type of power tubes being used today in comparison to the past. There are some companies that still make musical sounding tube amps. Like Canary Audio and Consonance. For me, I still stick with power tubes I’m familiar with and are known to be musical. 300b, EL34, KT66 amps etc. 

I will say what most are thinking in the back of their minds. We all think and feel that we know what we want in sound quality but we change are minds all of the time. Hence, why this has continued to grow as a hobby. We spend so much time trying to break down the specs of what a solid state or a tube amplifier can or cannot do. We get caught up in specs of the equipment instead of what it truly sounds to us. Everyone is not the same and can’t hear the same way. If this was true, the world would be boring. Now don’t get me wrong. Education before you buy is key but don’t be fooled by specs to decide how it sounds to you. Remember this article back in August 2003 from Stereophile;

https://www.stereophile.com/content/cary-audio-design-cad-805-monoblock-power-amplifier-sam-tellig-a...

One amp measured extremely well on the test bench while the other doesn’t. “The face-off of  Subjective vsobjective. Tube vs solid-state. Retro vs modern. Monoblock vs two-channel.”

Just because technology continues to expand doesn’t necessarily mean it is going to sound better. We at some point have to stop drinking our own BS (please step away from the ledge, lol). Example: Class D amplifiers. They have been around for a while and has improved some.  Ask yourself this question for those who own subwoofers within the last 10 years. Why do those Class D amplifiers fail within 5 years? Why are they not reliable? Put away the data and enjoy the music, your music.

Just because technology continues to expand doesn’t necessarily mean it is going to sound better.

Perceptive point, especially given that "technology" includes any number of different elements -- some which have progressed much more than others in the past 10 (or whatever) years. I'm not an amp designer so I don't know which parts have had big advances, nor do I know what design innovations there have been. So, to compare "tubes" and "solid state" seems pretty hard to do without a list of which types are involved and which specific parts, too.