We've been playing around with wireless audio transmission - there is a TI set of chips that are used primarily by a company called Anaren, who do drop in modules, that do basically cd quality audio over 2.4ghz - it has frequency spectrum hopping to avoid noise, and depending on the situation you can sacrifice range and buffer / delay for quality and bump it up to.....I think it was 24/48 - and it could do four channels (hence interesting us at the time). We may yet go back to it I suspect. When we played around with it transmitting across the factory and through two walls, it was as advertised - cd quality audio wirelessly, which was pretty rad. The only thing was that it would add some delay, so if we were to use it in quad, we'd need to have all channels delayed by the same amount - even a small perceptible delay can really screw up a quad image, turns out.