Hey Hirsch-
Applying ohm's law to the specs for the amps,
Power amps and preamps can have about the same gain (I'm comparing the specs for Headroom's website's spec sheets to a portable mic-preamp I have). For now I'll assume this must be voltage gain and not power or current gain because everything falls together then.
Headroom headphone amps are rated at ~20 to 200 watts depending on the model and load, while preamps are rated at, well I don't know really, but it stands to reason they must be low wattage line level amps.
So by reading an amp's spec sheet, getting the gain and watts output, and the impedence of the headphones, we could get an idea of how well the system would work together...
do I have it right?
seems right to me!...
If the gain is typically voltage gain and not power, why is this? Hmmm, bet it's because power gain depends on the load, while voltage gain does not......
sirion - if my assumptions here are right, then I led you astray in your thread when I suggested you compare the gain of your mic-pre to a typical headphone amp gain. Looks like gain is not the whole story...sorry....