I have the same issue. Tried grounding them but nothing helped. Also tried unplugging everything running on electricity in the same room. Issue persists. I also have a strong interference from the left speaker. Sounds almost like an old GSM phone signal. Tried with ferrite rings with no improvement. Bought some faraday fabric and put next to the active speaker. 99% improvement. Looks ugly though and can’t accept that solution really. Have you solved your issues?