[doctorcilantro]

Yes, I actually tried 5 psu's including his;l I bought a standard micro-atx PSU from newegg and had the same issue too. Each mini-psu has a 3 prong AC brick. His PSU was standard ATX.

I bought the Winmate and Electrodacus (eBay) said there is no better "brick" supply than the Lite-On.

The mini-Torii has a very sensitive input but the Eastern Electric 10 watt amp also had this problem, and it did not have variable gain.

It could be the DAC too. I don't have the 2nd DAC yet, and the Matirx DAC does not allow this noise to be passed out its headphone jack, but does pass it out on its single-ended RCA outputs.

I may have some cables which would let me try the Matirx XLR outputs though....

[davidR]

Jon, I thought you were using the XLR outputs all along, no wonder you had a hum! If you go from balanced to unbalanced this is a very common problem. I had this same issue in my home theater rig going from the RCA subwoofer output of my Marantz receiver to my Crown amp powering the sub. If your amps have XLR inputs you should be golden keeping it all balanced from the Matrix and shouldn't need the ground lift. It might even sound better than the RCA inputs.

[doctorcilantro]

Well I'm going from single-ended RCA>RCA (Matrix to Mini-Torii). and I had this same type of noise when I didn't have the Matrix but a Peachtree Nova, but then I would only get the noise (not a ground loop but direct PSU noise from PC) when connecting a DVD player to the Peachtree. I had an external 1616M sound card, not the Lynx, at the time. Same problem. I have tried so much hardware that I'm convinced these dc-dc converters have grounding issues....and they are supposed to be the last word in audiophile music servers. Wayne informed me the switching psu is to blame and of course the linear power supply is the soltution, but expensive, hot, and big.

There were times I had NOTHING connected to the PC and the noise would travel into the signal chain, when I powered down the PC, the noise vanished.

[davidR]

I see, sorry for the confusion. Those supplies do seem to be flaky causing you ground issues. From the look of their design it seems like they would radiate EMI too, no means of a shield or anything just plastic. Have you left the chassis grounds in tact? I know it hasn't fixed your grounding issue obviously but should help keep the noise down a bit in general.

[doctorcilantro]

Only one came with a 3rd wire to run to chassis and that was the one with the M10 case. No change.

I'm going to try grounding them all time the same outlet. Last not I tried all on the transformer isolated sockets of a Panamax 5510 and the noise was there. Maybe this exacerbates the problem; not sure if isolation means there are three separate grounds there even though they are plugged into the same conditioner.

[doctorcilantro]

Fascinating article:

http://www.boundforsound.com/tweak.htm