I attach a patch to support 24bits and 32kHz, 44.1kHz, 48kHz, 96kHz, 192kHz, all rates that appears in the screenshot submitted by Alan Alan.

I created also an asound.conf to correct the speakers positions. Since current driver only support 2, 4, 6 and 8 channels I specified it in the asound.conf but I'm not sure if this slave.channels should be fixed. The main problem is that by using asound.conf I didn't found any way to route to surround51 (or surround50 or surround40, ...) depending of the number of channels offered by the sink player. And when I play directly to hdmi, the AMP reports automatically the correct number of speakers involved.

Of course it would be nice to have this routes hardcoded in the driver...