Have the Brookstone IR-500... a wireless headset where the transmitting part plugs into the audio out. Don't have the headsets anymore but wonder what could be done to the transmitting part so audio could be heard in another part of the house. Is there a project here? Guidance sought
Do you have any technical details on the protocols/frequencies used? The name suggests it's using infrared (IR). Without that no chance.
Besides, good quality audio and Arduinos are not a good combination. The Arduino just doesn't have the horsepower to process audio much. At best it would be able to receive a digital audio stream and transmit it unchanged (e.g. act as receiver for your wireless system, then feed it to a digital input of some other device) - but without detailed technical specifications, no chance either way.