My astro mixamp barely had enough juice to get a decent volume out of my DT770 Pro 250ohm, I shudder to think what max volume would sound like on my K702 since these take about 3 knobs or so more on my super high gain amp.
And while the JVC-DH1 supports DTS, its technology for Dolby Headphone is a grade lower than the mixamp but it can also be better utilized with amplification since it doesn't have a built in amp to my knowledge.
Anyway with headphone mode enabled in a game like Bad Company 2 it is more pin point than my DT770 pro. With the DT770 I was able to get directional cues and sort of have a cone of fire idea of where the sound came from but on this headphones the cone is significantly reduced. So much so I was able to pinpoint hte exact angle someone was going to jump out at me from(I was hiding behind a rock, I could hear him and bam when he came out my angle compensation was spot on perfect with these headphones, no need to readjust my aim just pew pew pew. I was very very impressed by this right off the bat, definite afvantage.
The DT770's on the other hand have built in force feedback, as in you can feel the heck out of every big boom. Though... you can also hear the cage of your headphones rattle(some kind of resonance?). If you value feel in your explosions and want to sacrifice positioning these will be awesome. Just my 2 cents. With the K701/2 you can hear the explosions and they can be punchy as all heck(imo perfectly enjoyable) but you don't really "feel" it. At the very least no where near bass heavy cans.
Both need decent ampage to bring alive but if you have the right amp it is worth it completely. Now if you want to risk crackling, pops or slightly lower SQ in the name of positioning and 5.1 you can try connecting the mixamp to an actual amp or you can wait until someone inevitably makes another solution. At the same time gaming headsets seem to be headed in the wrong direction(6-8 speakers with a woofer crammed onto your head is probably the worst surround sound solution,,, so it is possible we never see it.
Found this thread looking for a mic mod, those headset mics seem to drown ambient nose better than say.. a logitech USB mic.
