USB DAC Recommendation

Okay, so here's the deal. I am technologically...well...dumb. I just bought into a Mach 2 system, but I haven't spent my dosh on a DAC yet. I want a good DAC. I want a DAC that's reasonable (5Gs or less), but I absolutely have to have a DAC that's simple to use connectivity/set up--wise. I'd also like it to have real hi-rez ability, not just a NOS DAC (unless I'd be a complete fool not to investigate those). What should I be looking for? Thanks all!