A post to the music-dsp list has mentioned the sonorus 16-ch PCI card
(PC and Mac).
http://www.sonorus.com

On their 'Technical Support' page, they indicate that they provide an
8ch mode WAVE device, as well as conventional stereo devices. Does
anyone have this system, or have direct experience of it? It would
appear to be the first commercially available device to offer this
important feature.

Richard Dobson