Left channel noise/imbalance issue

[udurbalanced]

When my Mjolnir SRM-006t is connected to my AGD D27, the left channel is much quieter than the right, and there's a beeping/static noise in that ear which responds to volume control. This happens to both my 950X and SR-007. The D27 is connected to my PC via USB, and does not exhibit this behavior when my computer speakers are connected via RCA. I've tried swapping the balanced XLR from left to right on the e-stat amp and and had the same issue, i.e. the issue didn't follow the balanced connection. I've also measured the voltage when the amp is on in the places indicated with identical results on both channels. Even with the D27 volume control bypassed the issue remains.

I've tried the following combinations for troubleshooting:

Cellphone -> Nuforce Icon HDP via RCA -> SRM-006t

No imbalance, no noise.

Cellphone -> Nuforce via RCA-> D27 -> SRM-006t

Imbalanced and some noise.

PC -> D27 -> (via RCA) SRM-006t

Imbalance and noise but not as severe as with XLR.  

 

It seems to be the estat amp that's the issue, and I was told in the Stax thread it's either grounding or in the volume control.

 

Any thoughts/troubleshooting tips?