I am sending the output of Bela (with a CTAG cape) to an amp (SMSL SA-98E) driving a speaker.
At the same time, I am sending 4 outputs from the Bela to my RME Fireface UCX interface, connected to my laptop. Whenever I plug the 4 cables into my interface, I get a noticeable hum as well as what sounds like digital noise. If I unplug the power cable from my laptop, this hum decreases, in particulat the digital noise. I am powering the Bela from the barrel jack, but even with the power to the Bela unplugged, the hum persists.
The hum is only present in the amp and speaker, not the inputs to the interface.
I suspect it is a ground loop, but not sure how to address it. I have looked at the many similar discussions on the forum but not sure, which, if any, of these apply to my situation.