after much experimentation and listening, it seems it is a much better idea to connect the headphone directly to my soundcard lol...
I was connecting them to the 20db amplified output of my klipsch promedia speaker control pod, and although they were receiving enough power, they sounded a bit bright. the amplification does something very strange. not so sure I trust what it's doing to the signal...
So, I connected them straight to my audigy 2 zs (I verified no clipping with the udial.ape file - I have Vista resample everything to 48khz anyway, so the audigy's auto on-chip resample doesn't get confused) and now the sound is warmer (highs are less harsh) and bass stands out more.
They are definitely receiving enough power (for now
), without an amp, from the headphone jack of the soundcard. I'm sure the 250ohm impedance of these phones is good for the headphone jack, as it is not too low- i.e. not trying to pull too much power (current) out of the jack.
sounds good to me! these headphone, for $108, are fantastic.
everything from tool (of course) to portishead, massive attack, primus, mahler, rage, soundgarden, pink floyd, heart, jefferson airplane..... you name it.
good stuff.