I have contacted the manufacturer but they are not familiar with the issue. According to them they have confirmed general compatibility with Linux. But they cannot guarantee compatibility with every distribution.
I don’t know what USB interface Arcam uses right now. With the first irDAC (and the DA-33) they used an interface developed by DcS. I assume they still use the same technology for the irDAC II. Since 2 weeks I have a DcS Scarlatti Clock in my main system with USB input connected to another RPi using M2P and Squeezebox. And SPDIF + Wordclock output to my DcS Puccini. This setup is rock-solid. Although a bit ridiculous to drive a EUR 35k (original price) setup with a EUR 35 piece of hardware…
Anyway, I’ve tested the irDAC once more this weekend on my system in the kitchen. Still the same result: after 7 hours I heard only crackling noises. After a ‚kill‘ (shutdown didn’t work) and a restart of Squeezelite, it worked properly again.
I have given up on this setup for my system in the kitchen and moved back to the Allo BOSS DAC. The Arcan irDAC is now running (without a glitch) in my daughters macbook based setup.