I know Wayne will have a good answer for you but I can say that I recently finished the Thermionic 3pi and use it with a SE 300B amp. Wow -- I've had some nice speakers in my system, but these blow all others away. The 300B's have no problem at all with them, bass is full, detailed and powerful, highs are clear but not silibant, imaging is very tight. I think the technical answer to your question is that one speaker, or series of speakers may make a better match due to the impedance rise at resonance. SE amps without feedback have a harder time with this than, say a low impedance solid state amp with lots of reserve power. As to which makes the best match, Wayne's the expert there. Steve