I'd love to be able to get 2-channel audio cloned to the rear channels with either my VIA's onboard audio, or with my M-Audio Revolution (the latter is preferred because of its significantly better signal-to-noise ratio). However, it looks to be extremely difficult if not impossible to do that, and then there's the matter of mixer applications...they're horrible! Audio seems to be the major area of desktop computing that Linux is lacking in.
Thoughts? Ideas? Am I missing something that would make this really easy? (splitting front audio to the front/rear inputs of my amp isn't a very good way of doing it, I like being able to change my front/rear volume levels independently)