The modules required for usb sound support are here: https://www.dropbox.com/s/35tzoscryoo8xh3/AX56_sound_modules.zip?dl=0
They do work with the newest Merlin firmware, downloaded from the official page (384.18-alpha1). Tested with alsa and mpd.
As for video, I have this issue:
modprobe -d /opt/...