I don't know if it really is mono out, but it sounds like it from your post. If it's not supposed to be, I'd contact HTC or your carrier to get a replacement. Yeah, I know, the headphones that come with it aren't the greatest thing in the world, and I really wish they added a stereo mini RCA onto the phone hardware, but you might have to either deal with it, or get a nice set of stereo BT headphones.
