Hi,
yesterday I installed OSMC on a Raspberry Pi 2B. I also connected a Behringer Firepower FCA610 USB Audio Interface for surround-sound with my analog multi-channel power-amplifier.
Whenever a DolbyDigital video is played OSMC decodes the AC3 into stereo for speaker setups from 2.0 - 4.1. If 5.0 - 7.1 is selected, there isn’t any sound at all,
Does anyone have an idea how to debug this?
Thanx for any hint! 
osmc@osmc:~$ cat /proc/asound/FCA610/stream0
BEHRINGER FCA610 at usb-3f980000.usb-1.3, high speed : USB Audio
Playback:
Status: Stop
Interface 2
Altset 1
Format: S32_LE
Channels: 10
Endpoint: 2 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000
Data packet interval: 125 us
Capture:
Status: Stop
Interface 1
Altset 1
Format: S32_LE
Channels: 6
Endpoint: 1 IN (ASYNC)
Rates: 44100, 48000, 88200, 96000
Data packet interval: 125 us
Video example:
Codec: AC-3 (ATSC A/52)
Channels: Surround 5.1
Sampling-rate: 48000 Hz
Bitrate: 384 Kb/s