AirPlay issues with USB sound card

Hello everyone!

UPDATE:

Ok so i remembered that i changed from analog audio out to a cheap external sound card shortly after reinstalling osmc, and putting the audio cable back into the 3.5mm jack solved my problem. Now it’s just the noisy crackly audio again, any ideas how i could solve this problem with the usb sound card?

I’d like to know if anyone else has similar problems:
On my rather recently installed osmc, I’m using the built-in Airplay function
to stream music from my notebook with iTunes 12.3.0.44.
For a few days now, iTunes intermittently sends double the data
to my Pi via the network (verified by speed monitor and task manager)
every other song, causing the music to stutter infuriatingly.
I tried reverting to an older iTunes version (because it used to work
perfectly with iTunes 11) but my .itl can’t be opened by older iTunes versions
and I don’t have backup itl’s, because of a recent crash.

Any thoughts on how to diagnose the source of the stutter? Network rates go from 100-150 kB/s in normal streaming mode to 250-300 kB/s in stutter mode. Thanks a lot in advance for your comments! Cheers