I do not believe the USB port will work for headphones o the Q. The small jack is actually a mobile phone size jack, instead of what comes on non-phone PDA's. You can get some good stereo headsets designed for that size jack or you can get an adapter at Radio Shack or from a search for retailers on the net, that will allow you to use standard size plug headsets.
Some people have opted to use stereo bluetooth headsets.
Rob.