I just moved from a 2-year-old built house, to one from 2004. The same exact setup I have is now creating noise I didn't have before. Setup is: PC -> Matrix Quattro II DAC -> XLR balanced out -> Mackie 402VLZ4 mixer -> Adam AX3 powered monitors. All connections are balanced even though cables are TINY (about 2ft each, for all involved). I just had them handy, so why not. I've not tried with RCA cables yet. What could be causing this? I have had that before in the past, but typically it went away after a few days (which in itself is weird... I was using a different DAC back then). I hope it's not bad grounding... The house is from 2004 so it's not all THAT old. The noise is NOT impacted by either PC, DAC, mixer, or monitor volume. It stays at the same level no matter what. Thanks for any tips! EDIT: I have all my plugs into a protected power strip, a large Anker unit. I also tried plugging JUST the monitors into my Furman SS6B, which is plugged straight to the wall, and with nothing else to it. But this made it worse! The noise got louder and more frequent.