I wouldn't lump DSP and tubes together as the same thing.
They aren't.
When someone uses tubes to tame some brightness, they may as well use DSP or experiment with different power cords or get a pre amp with tone controls.
Tube pre amps and amps have certain euphonic characteristics that their solid state cousins do not.
And solid state gear has it's own colourations.
What you prefer is the type of amplification that sounds right to your ears when used in your system.I can control the sound of my system, with tube or solid state amps, but they won't alter the sound of the room.There is a difference.And that should make sense.
I use a low wattage SET amp running tube rectification and 2 EL 84 output tubes.
I 've owned OTL tube amps, PP tube amps, EL 34 and 300B SET tube amps and several solid state amps from class A, AB, and D.
None of the amps made my system sound the same.
But they can't alter the "sound" of the room the amps are in.They only alter the sound of the gear as heard in that imperfect room.
Correct the room, and differences in amps becomes even more evident.
This is where a DSP unit comes into play.
Or room tuning devices.
If you have a bad sounding room, with no room treatment, poor speaker placement, it doesn't matter what type of amp you use,it won't eliminate the room problems.But a DSP used with any of the amp types above can change the way the amp and gear interact with the room,and transform the room electronically from bad to good.
Having said that,every link in the chain has a sonic signature, irregardless of the circuit or configuration. Everything influences the sound we hear coming out of our system, from the power from the panel, thru the wires and circuits and fuses and crossover and drivers etc.
We either accept the sound as it is or we tinker with it, and when that doesn't please us we try other gear or quit the hobby and become just another disgruntled former audiophile with an axe to grind.
Time has marched on, tube and solid state gear made today has less colourations than the gear made 40 years ago.
What I find sad, not funny, is that this doesn't make sense to some folks still in the hobby today.