Ian, in thinking about the above design you posted, I realize that it WOULD be something I would be interested in as well, although the form factor being similar to the AxiomAir is not necessary in my case.
I was thinking last night that such a unit, at a reduced cost without the amp, drivers, crossover and possibly the elegant form factor would allow someone like me (who has multiple "traditional" systems everywhere I spend any time) to STILL offer room-to-room "whole house" music continuity at a less-expensive cost than buying a full AxiomAir for each location.
I guess this is really what a SONOS system offers....I've never really checked into that. But it would keep within the A^A architecture and GUI interface.
