Need help solving hum problem

Yes, it is.

Well from experience in hooking up litterally hundreds of sytems over years, I can get rid of pretty much any hum from tinkering a bit I suppose. Usually you should first try using a cheeter plug on one of your 3 prong plugs, either on the preamp or amp first.(they'll all still be grounded through connection to one another). Usually, this solves the problem of blatent hum off the bat. Sometimes interconnects or speaker wires are running next to power cords too closely for stretch, and can have hum in the wires that way, but usually not. I have run speaker wires next to high voltage cables with loud buzzing and humming, that's to be considered.
I once hooked up a really really long pair of Interconnects down 2 sides of the room, running along the same path in a wall with some power cords, and it buzzed like crazy.
Anway, hope that gives some food for thought. But I think you might try the ground cheater plug thing first. That usually works. Then, you can try moving your interconnects around, while your system is playing, and see if it's a problem. You might find that if you get the interconnects to lay in a certain way, you'll virtually eliminate hum sometimes.
Good luck

Thank you. I had tried a cheater on both the DAC and the preamp, with no success. I will try it on the amp, but as I said, the hum goes away if the amp and DAC share the same wall outlet. Based on the results of my various troubleshooting attempts, I don't think that the location or proximity of components and cables is the issue in this case, but I do appreciate that those can be factors in system noise.

I have tried EVERYTHING known to man to minimize the hum that i'm experiencing. I'm wondering if it doesn't have to do with how these designers are are using the upsampling devices and trying to keep circuitry to a minimum ???

I recently did a "tweak" that did help this out a bit while making other noticeable improvements though. Since this applies to and can benefit ALL systems, i don't want to "pigeon hole" it to this thread. Look for a new thread on the subject in the next 24 hours. Sean
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(a bit chagrined...) I thought that I had tried lifting the ground on the Dodson. But I happened to try it again, and it seems to have fixed the problem.

Nevertheless, I will attempt to work through the process Sean describes in his excellent other post.