DSP > multiple drivers
I spent a good while researching before buying a gaming headset recently and most informed places (headfi.org and AVScience forums) tend to agree that the cheaper Tritton AX720s with their DSP-based surround are in fact better:
There's fairly universal criticism for the Turtle Beach equivalents being too flimsy.
I have the 720s and they're great.
Shameless blog plug here but I wrote a post about Dolby Heaphone and I included some sound clips with it enabled for comparison. You can try it with normal headphones here: