Newby alert - but I don't know how to get this bug to the developers
I have been trying to work on a fix for Bug 1498129 - https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1498129 on Ubuntu
My USB soundcard is an Asus Xonar U7 Echelon Edition https://www.asus.com/Sound-Cards/Xonar_U7_Echelon_Edition/ which identifies itself to alsa as "Xonar U7 Echelon Ed." The card is supported by alsa and works well in analog mode but I cannot get digital output via alsa.
It has iec958 as device 1 rather than device 0 and I can access digital output by referring to directly to hw:x,1 but cannot access digital output via alsa.
Attempts to change the iec958 device in USB-Audio.conf fail because of the period char and apparently my level of OS (Mint 17.3 based on Ubuntu 14.04, kernel 3.19.0-32) does not have alsa supporting USB vendorid:productid naming so I don't have a workaround.
If a patch exists, advice on applying/rebuilding alsa would be gratefully appreciated.