Thanks guys. The reason I asked was to see if I should get an external soundcard (for virtual effects) or just get a DAC/amp to boost stereo. Only problem is I'm gonna be on a laptop and I need whatever I get to be easily transportable, which cuts down on available options.
The cans I have are not high-end and are easy to drive, so I might just stick with onboard "HD" audio for now (at least it supports X-fi virtual effects through additional software/drivers if I want to dabble).
I had already ordered the Asus Xonar U3 but will probably end up returning it because it now seems little more than a glorified Dolby Digital processor. From what I've read, it doesn't seem like that's so important in movies/games after all. Perhaps I am wrong; I'll try and update once I've had a chance to play around with it :)