Hi daiwek!
Onboard audio has come a long way in recent years. Audiophiles will still swear by high-end soundcards (and for good reason), but that's not to say onboard 7.1 audio isn't still great - i have an asrock mobo as well and have been more than pleased with the quality of its 7.1 audio.
In regards to models: all the Corsair headsets I've tested have performed quite well, including the 1500. The 1500 is one of their better wired headsets out there for under $100, and the build quality is surprisingly good. The steelsseries 7h are also good, provided you purchase the 3.5mm kind and not the USB kind, but I've heard they don't quite warrant the $130 price tag (at that price there are better models)
If you wanna go to the next level up, the
Beyerdynamic MMX 300's are getting insane reviews, and the Sennheiser HD555 are equally as impressive. It all depends on how much you want to spend. Just remember- you can still get high quality sound from onboard audio!
cheers,
-audioranger