Quote:
Originally Posted by
icefalkon 
Question...how high impedance can's can this X3 drive?
Hmmm....that didn't come out right...but you get my drift.
Generally there is no upper limit on impedance for a transistor based amp, with higher and higher impedances being driven better and better (since a high impedance represents a small load and smaller loads are easier to drive then big ones). However, its hard to design high sensitivity headphones with very high impedances, so you may find that high impedance headphones have few dB/volt and thus require an amplifier with a very high drive voltage to reach high volumes.
So the short answer is that you need to look at the sensitivity of your headphones. If its very low, you may have a problem.