The specifications state that the S/PDIF I/O is 20 bit. Does it not support 24 bit ?
The Gold Channel both receives and sends 24 bit audio, also on the S/PDIF I/O.
The S/PDIF standard is actually 20 audio bits - and 4 auxillary bits - which is the reason why the 20 bit are stated in the tech-spec's. (Today almost all pro- or semipro digital audio equipment use the 4 auxillary bits for audio LSBs).