Turtle Beach TBS-2100 7.1-Channel Dolby Surround Sound Processor for $51.99 shipped. Here is a screenshot for your reference. This DSS processor works with any stereo headset or headphones, as well as Xbox 360, PlayStation 3, PC and Mac, and features headphone amplifier with variable bass boost, digital optical and analog stereo inputs. Most places have it for about $61 or more.
Ear Force
Ear Force X41 Digital RF Wireless Audio+ Chat with Dolby 7.1 Sound for $149.54 Shipped
Ear Force X41 Digital RF Wireless Audio+ Chat with Dolby 7.1 Sound for $149.54 shipped. Here is a screenshot for your reference. It features digital RF wireless with up to 30′ range, pure-digital sound transmission, digital input pass thru to allow the X41 and a home theater system to be connected simultaneously. Its transmitter is powered by USB with no AC adapter required. As a comparison, Best Buy currently has it for about $199.