To be honest, with all the various different solid state and tube amps I tried that day, the headphones itself and their tuning would infinitely make a bigger impact on its sonic characteristics than an amp will. It was virtually impossible for me to judge any kind of amp without a proper a/b test and it would've entirely been dependant on possible placebo without it. I can't imagine the Diana Phi TC sounding all too different on a drastic level on an equivalent tier solid state amp as opposed to the tube amp it was hooked up to in the room. I understand your concerns though.