Sound quality was better than we expected with an RF signal. While the X31 cannot decode Dolby Digital, it does do an excellent job of stereo separation. For example, during our sessions with Call of Duty 4, we could easy differentiate where gunfire was originating off screen.
The X31 also has an onboard sound effect button that has three settings. The first will initiate a bass boost, which we actually enjoyed. Explosions and other powerful sound effects carried more of a presence with the setting activated. The next effect was similar to what we heard with the P21s, something called "widening." Again, we weren't thrilled with its performance, so we just stayed with the bass boost. If you like both the widening and bass boost, the third setting allows for both to be active at the same time.
Next in our testing was chat performance. Using the included white Xbox wire, we connected the controller to our headset. While it's not the ideal totally wireless setup we'd like, it does work well. Best of all, you can separately control the chat volume on the fly, so game audio will never drown out the chatter you need to hear. Turtle Beach also includes a feature called Chat Boost that raises chat audio when game audio gets too loud. While we welcome this sort of technology, you'll probably wind up making adjustments yourself anyway.
One last note about the wireless experience the X31 offers: Since it operates on the 2.4GHz spectrum that routers and other wireless products love as well, you may get some interference while playing. While this is mostly unavoidable, we recommend separating the two items as far apart as you can. If all else fails, try assigning your router to a certain wireless channel and see if that helps.
Priced at $100, you may want to make sure you'll be able to get more use out of the X31s than just Xbox 360 gaming. Since the boom mic can be moved out of sight, there's no reason you can't use it for TV and movie viewing as well.
We would have been impressed if the X31 was able to deliver Dolby Digital at its $100 price tag as we've yet to see a headset do so for that price. If Dolby Digital is something you're after, check out the X4. It might be twice the cost, but its excellent sound quality and 5.1 reproduction in-ear creates an immersive experience.