The AON MDH-501H/D headphones from Wave-on offer 5.1 stereo surround in what is probably the largest headphones ever conceived. The unit comes with a dolby decoder that supports SPDIF/Optical.
Seriously, look at the size of these things. It looks as if the setup is aimed at gamers, but I suspect you could cause neck trauma by wearing them for too long.
It will be available later this month for 149,000(KRW), which converts to about $160USD.