So against all recommendations i tried another arm-board: an Orange PI Plus. And the warnings were true: it tends to run hot (heatsink isn’t mandatory), had to port a GPIO LIB myself, onboard wifi interferes with audio..
But that being said, specially thanx to a member of the forum who build a old (3.4.39) but decent kernel and shared it on github, it does the job flawless where i just could not get done with a RPI-2.
This is probably due to the 4(!) USB host’s in the used socket, so network (eth/wlan) and USB ports don’t share 1 USB host.
I think my problem with the RPI-2 / MC-arm / my-Xmos-USB-receiver combination come’s down to the single USB host on the RPI. If the RPI is used as a pure DLNA music render it can’t handle IO in a way that the latency sensitive USB receiver can cope with. The main cause is the MC server-client setup tries to get the whole media file in as quick as possible at the start of each track. This stresses the IO scheduling through the RPI’s bottleneck.
Playback from a local HDD works fine; actually playing form the music share of the server goes very well.
To illustrate this see enclosed screen prints.
The server-share with music is mounted on the RPI (smbclient, samba is running on the server anyway) and is imported in the main library.
The print screens are form the same event (change of DSD tracks), one with “Play local file ....” enabled, the other disabled.
So in both cases the exact same mediafiles form the same location comes out of the speakers.
If it receives the mediafiles through DLNA it stresses the IO too much and (in my case) causes drop outs...
In Conclusion:
I know it could be specific for my hard ware; but it is a kind of a pity MC raises a task: get the hole mediafile a quick as possible, which gets in it’s own way.
However i’m happy to get it working with the Orange PI, and if there are future developments for the arm-platform happy to test them!