My main system has been blessed by what seems to be unusually clean power from the wall, but I haven't had such luck at my computer. 99% of my computer listening is done through headphones (Topping D10 > JDS Atom > Sennheiser 58X) but I'm going to add some powered monitors just for the sake of convenience, and my experience with them so far (with zero power conditioning) has been a very high noise floor.
I'd like to keep my spending to an absolute minimum, since this is a secondary setup within a secondary setup. Anyone had success killing the dirty line noise that makes its way into super cheapo plate amps using a Tripp-Lite Isoblok (the 2-outlet Isobar that sits flush with the wall)?