Question

Thanks for the response Alex,

To clarify, I'm wiring the speakers directly via an unbalanced RCA cable rather than pairing via Bluetooth. The room is upstairs far from a kitchen and no microwave is running. I've used Bluetooth devices elsewhere in the house (and outdoors) with no interference issues. I've also used other Bluetooth-enabled speakers - wired similarly - in the same room with no issues. I understand some devices may be more susceptible to interference than others, but this one has me stumped.

Answer 1

You said it right there "unbalanced RCA cable"

Unbalanced cables are very susceptible to picking up interference. In fact these act more like antennas than they do audio wires depending on where they run.

Replace them with shielded Unbalanced Cables and see if that solves your issue. Make sure to use quality cables and not the spool you find at the big box store or the hardware store. Use brands like Mogami, Pro Co available from Sweetwater.com, Guitar Center, or any quality audio stereo store that has a high end audio department. Avoid anything that looks like zip cord or lamp cable. Don't use cables that are crimped in plastic like Hosa or any of the cheaper unbranded cables.