Indeed, @jonwolfpell. I wince when I see someone describe an amp as adding "tube warmth" to the sound. That’s not what good tube amps do; what they do is not create the "cold, hard, dry" sound of bad solid state. I always loved the term J. Gordon Holt used to characterize the sound of the best tube amps: liquidly transparent.
I vividly recall the first time I heard "grain" in the sound of electronics. I was already aware of the term and concept from photography, and to then hear tiny little "clumps of sound" in the sonic "picture" a hi-fi was creating (one with solid state pre and power amps), in contrast to the grain-free liquidity of the sound the ARC system (pure tube, not hybrid) I was comparing it with was creating, was clearly audible.
The appeal of tubes to me has always been not what they add, but what they don’t.