I had a similar issue a few days (or so) ago - updating was done today, unfortunately, it did not solve the problem. RIght now I run OSMC Kodi 15.2 Sep 28 2015 , Kernel 4.2.3-3-osmc, its a digi+ 1.0, and on a Pi-1-B+
(Nice thing - originally, the card was automatically detected on installing osmc - I just had to select it in the audio-hardware settings).
I’m trying to do as you wrote, but changes made in Pi Config are not stored. After setting to “hifiberry-dacplus-overlay” and confirming by OK button changes are not stored Anyone can help with this issue?
I’ve got OSMC Deceber 2015 version
EDIT I managed the problem by editing config.txt file manually but configure by Pi Config still doesn’t work.