ASUS Xonar Essence STX is, as far as I know, the only sound card with integrated headphones amplifier.
I could buy a stand-alone amplifier, but that would still get the sound from my Motherboard's on-board sound-card, which isn't stellar.
Consider that the PC is my main source of music (>95%). So in this case, I would probably waste money on an amp, right? I would need a good sound card first, then an AMP. So the Xonar would be both.
What output (in mw) does this card have? I haven't found it anywhere. Some untrusted source said 140 mw. That's lower than even cheap amps. But Sony MDR XB 1000 which I want to buy appear to be working with 100 mw, so that would be ok, right? I have no idea what connection there is between mw, Ohms and decibels ::- ). Ok, I do have some idea: mw is power, Ohms is electrical resistance and decibels is actual loudness.