The SGI version of PD can not play or record more then 2 channels. I've fixed
the problem and it's now possible to play or record up to at least 8 channels.

There was a mistake in the file: s_sgi.c The AL calls at line 142 and 147 was wrong, the corrected code is:

ALwritesamps( oport, buf, outchannels * DACBLKSIZE );

and

ALreadsamps( iport, buf, inchannels * DACBLKSIZE );