Maybe the E90 and ESP95x would work better with just a simple standalone DAC, without a built in amp? And maybe that's why you're getting some hum coming through from the Sony dacamp. That is my best guess at this point.
If so, then this may not be a grounding problem at all. (In which case, it might be wise to remove the ground from the Sony dacamp before it can cause any damage.) And perhaps just a simple matter of swapping around some components.
If you don't have a simple standalone DAC handy (which can be had quite cheap from any Best Buy btw), then you might try just running the RCA outputs from a CD player into your E90 instead, to see if you get any hum from that. And turn all the other stuff that you're not using off.
If so, then this may not be a grounding problem at all. (In which case, it might be wise to remove the ground from the Sony dacamp before it can cause any damage.) And perhaps just a simple matter of swapping around some components.
If you don't have a simple standalone DAC handy (which can be had quite cheap from any Best Buy btw), then you might try just running the RCA outputs from a CD player into your E90 instead, to see if you get any hum from that. And turn all the other stuff that you're not using off.
Last edited: