Audio problem with windows phone.

This is probably a quick fix and I am not seeing it, but whenever I plug in my headphones on my Radar 4g, the audio is mono, and is only coming from the left speaker. I tried hooking the phone up to my reciever and sure enough, it was mono too. Now I want to use this thing as a replacement to my zune HD, but I can't really do that when sound is only coming into one ear. Anyone have any suggestions to fix this?

Added info: The headphones are of course stereo, they're Sennheiser HD 280 pros. The reciever is Techwood, and the channel was indeed set to stereo.