My (Razer Blackshark) gaming headset does that - the actual headset has a 3.5mm jack on it but the "guts" is a USB DAC with some THX stuff supposedly built in (questionable utility but most of the games I play don't support it anyway) - I figure they reuse the same headset components down the market and just don't ship the DAC, it works flawlessly under Windows/Linux so no real issues with it and I can use it with any other set of wired headphones (of similar impedance) which is nice since headsets wear out eventually but the DAC is solid state so should last much longer.