Hi Roman, hi all... intriguing post and interesting questions, as I've been for about 20 years a triode and, before, a tube user and a glowing-in-the-dark maniac.
I purchased - years ago - an Hiraga 20W which I used as a bass enclosure amp when (badly) multiamping with Pioneer D-23, and I loved the Altec 416A punch with such an amp; then I put on a shelf for a couple years, while I used Partridge/300B SET monoblocks, preferring their romantic musicality, from time to time I tried to use the above mentioned 20W Class A, BUT what I remember was "poor musicality" - i.e. listening fatigue, bleached, innatural dynamics and harmonics... I moved in and out of my system at least two-three times.
... so I gave up...
Nonetheless, in the meantime, I purchased for nice prices one more Class A 20W, then another one and finally The Mighty 30W Le Classè A, the most expensive (back in the late '70s) and sought-after Hiraga/Lectron's class A power amplifier, with its 1,5 Farads, a beast made in extremely low numbers... finally, I purchased a Le Monstre 8W for peanuts, also impessively sporting 0,7 Farads (consider the 0,5 Farads of 20W Class A).
It was a frenzy, as I sort-of became a traitor of triodes... my friends didn't waved hello, anymore, when meeting in the street;-) - BUT also a great chance to obtain those "fabled" perfect squares from cartridge/tape/live radiowaves/disks to horns.
During the recent, first days of October, overhauling and measurements to my speakers system, looking forward to the new bass horns in the making (poor me...), Franz Hinterlehner wanted to measure ALL my amps to know their sensitivities and that's why I had ALL my power amps, triodes and solid-states, handy.
Next step was to put in use the old Goto CF-1 3rd order fixed frequencies electronic crossover, 220/1000/5000hz... so, why not, we connected all that mess and... must say in the bad grounds loops and cable mess, I recognized a gem of sound;-)
Like from crap comes a flower...
When I was quiet enough and lonely, I optimized ground and... wasn't able to understand what happened to my little studio and the sound coming from Gotorama: it was ALL like when using SET monoblocks for the four ways, only MUCH, MUCH better: voilà, gone that annoying sense of coldness and innaturality, sound also after two full weeks without music, is still so well carved in my aural memory: smooth, liquid, full of lively harmonics, absolutely uncompressed and easy to the ear.
I was hitting me for such a late trial with (good) solid state... just before the flood (thanks to His Bobness for lending this;-)) I was having multiple orgasms, as virtually all disks and discs I listened to with FULL solid state multiamping was a double shot of same fix... I mean had to re-listen to same disc/k(s) twice to re-enjoy this... beauty.
So: where was the compression and sense of inadequacy I previously experienced with a single Class A 20W?
I cannot reply... boundaries between ESP and electronics are dangerous when put together... anyway, someone wrote about "blurred" sound when talking about triodes... must say, regretfully, I agree.
Every note now owns its own life and sparkling light and... it's both new and old sensation... like "ohhhhh, finally at home" stuff...
I planned, when mud-free again, to re-listen to a friend system using a mix of PP triodes (300B) and class D and T-amps with his large Onken/Altec/TAD/Goto speakers... I don't remember he obtained such a result - i.e. full class A cure as I'm using now - so, maybe it's a matter of interaction, balance and common sonic footprint... the most technical oriented (not me, my fault...) will find more apt explanation(s).
Sure is my satisfaction... maybe a flawlessly measured square waves at oscilloscope isn't so unmusical to the ear, don't you?
P.S. - when I first listened to Le Classè A 30W with a single speakers Zeiss Ikon/Klangfilm when I turned OFF amp, music continued, unaltered for about 90 seconds... then suddently dimmed...
"Use your ears as your eyes" - Gertrude Stein