Question

Hunting some noise gremlins in my setup.

PC USB audo card (soundblaster g1) via 3.5mm to RCA to Eris E3.5 = no problem, very clean

PC USB audio card (soundblaster g1) via 3.5mm to Sub8 to Eris E3.5 via RCA cable = electrical noise made worse by mouse movement?

Tried a few different cables, isolating power and input device cables, even ferrite cores (desperation)... no difference.  USB bus/motherboard to blame?  Maybe the RCA cable?  Switch to TRS between Sub and E3.5s?

Answer 1

Get an external/better audio interface so you can connect your speakers with balanced cables. Cheap PC audio cards are notorious for this noise problem when moving the mouse around, or when the CPU or GPU is processing. Or just buy a Mac.