[AndrewA]

I recently installed a new power supply in my desktop. Everything works, but I have acquired what sounds like a ground loop hum in the speaker with the on/off switch and volume control (and the hum gets louder as I turn up the volume). There is no hum in the other "satellite" speaker. The power lead from the woofer unit only has a two-pin plug on it, so there's no chance of using a "cheater" plug to lift the ground, although it seems as if that wouldn't have worked anyway.

Any suggestions?

(FWIW, the wiring scheme is pretty standard. A lead with a stereo minijack takes the two-channel audio from the back of the CPU to the back of the speaker with the on/off switch and volume control. Another thicker lead from the back of the speaker goes down to the "woofer" with a multi-pin connector going in to the woofer. A second thinner lead coming out of the same multi-pin takes audio out to the other "satellite" speaker. A separate power cord from the woofer goes to the power strip.)

[ebag4]

I recently made some changes to my system (added a USB DAC) and ended up with a hum that would increase with volume.  I tracked it down to the monitor, when I put a cheater plug on it and the PC and the hum disappeared.  Of course the cheater plug should only be used to troubleshoot and not a permanent solution.

Good luck!
Ed

[Hap]

Is the hum low frequency.
Hum picked up in the audio outs could be due to many things, but since you just changed your PS; suspect your sound card or cables is picking up RF/EMI from the PS.
Try separating your audio out cables away from your power cables and off the floor.
Also you can try putting your audio card into another PCI slot farther away from your video card.
If you do trace the hum back to orientation of your AC plug, then adding some felix filters to your PC could also help a bit.

[Folsom]

These could help.

http://imageevent.com/cics/v03theartofbuildingcomputertrnsp

http://www.head-fi.org/forums/f46/usb-cable-matters-371033/index2.html#post4849163

(scroll down to pictures)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=51381&perpage=25&pagenumber=95

[AndrewA]

Thanks much to all.  A thorough unplugging and replugging of all connectors, and a careful redressing of the routes of all the cables, seems to have done the trick.