Spit balling. Given that many on this forum have spare DACs and amplifiers, connect a cheap DAC to the USB output, wire the signal wires from each channel to a mono to stereo passive adapter and experiment with Hafler surround sound. Good enough for the living room environments where the Wiim is most likely to be used?
P.S. Not responsible for any damage to your components. Seriously, doing this with electronics with outputs that do not share a common ground can burn out your equipment.
P.S. Not responsible for any damage to your components. Seriously, doing this with electronics with outputs that do not share a common ground can burn out your equipment.