Indeed the Merlins are intended for tubes. So much so that at one point Bobby had a "tube" version and and "ss" version of the speaker. To me, the Merlins are unforgiving in the sense that they will let you hear your amp and it doesn't candy-coat (maybe to strong a word), put a great tube amp in front of the Merlin and you will get balanced sound. SS has always been a bit problematic for some listeners. Besides the impedance issues with SS versus tubes, the Merlin speakers do not need very much dampening from an amplifier, again, ideally suited for tube amplifiers that most users will us with the Merlins. Love ProAcs too. But that's why there are different products on the market. For me the Merlin is the speaker of choice for two-way speakers and the coherency of that, with enough bass to feel like you are getting a three-way level of bass for most music.