[Krobar]

I suspect the Pi2 is not a strong enough CPU to decode 5.1 DSD, I have the same problem. It would be great if we could use DSD bitstream for those of us that have compatible amps.

Multi-channel files are problematic. If I use either the default PAPlayer or DVDPlayer, the music stutters badly. I noticed my receiver showed fs:96KHz, so I thought the sample rate might be too high for the RPI2 to handle in 5.1. I found a work around that allows multi-channel files to play mostly correctly. If I set the System - Settings, Audio output to the following, I get stutter-free 5.1 playback with DVDPlayer. PAPlayer still stutters though.

Read this thread. If you update firmware manually it should fix the issue. Fix should be in future OpenELEC updates.

My firmware version looks to be new enough already. This comes with yesterday's build #417:

# vcgencmd version
Apr 11 2015 17:37:07
Copyright © 2012 Broadcom
version 311b05fb4e33655a083a6f65b645e6a14e322803 (clean) (release)