If you overdrive a solid-state amp, you get "square(ish) waves"...which have a "squanky," irritating sound. I have a forty-buck solid state amp I use occasionally as a practice amp...so my comments are based on experience more than theory!
As far as re-creating a triode amp, that could be a problem! 12AX7's are still available for initial stages...but most of the "power tubes" currently available are beam-power pentodes of the 6*6 (6V6, 6L6, usw.) sort...or TV-set horizontal-output tubes, also generally pentodes!
Dunno where one might find 2A3's...
Steven C. Barr