One of the big differences seems to be the size of the power supply and heatsinks relative to the power of the amplifier, ie the degree of "design overkill".

In other words, a "high end" amplifier can loaf along at the same levels which an equally rated "cheaper" amplifier can only sustain for a little while without overheating. The bigger power supply also seems to help with stability and keeping distortion #s low at high outputs.

There is also a whole debate about output impedence (aka damping factor) and its effect on the "tightness" of the sound. Big amplifiers tend to have a higher damping factor and, if you buy into the story, can give a tighter sound at low frequencies and high output levels.

Conventional wisdom seems to be that the effect of damping factor has been disproven but I remain unconvinced.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8