Try lifting the ground on one of your preamps. I had the same issue with my setup also, ARC Ref3 & Meridian G68. You may also have to lift the ground on your sub if it is connected to both preamps.
how to eliminate another anoying 'hum' from tubed
I never had a ground loop hum before; but I decided to upgrade my gear from a Meridian 861/hd621 switch and G-98 to a VAC Phi Beta tubed preamp, PS audio perfect wave d/t, and a new Marantz 7005 a/v processor. I am using a Parasound A-51 multi channel for center and rears, Velodyne DD-15 sub; Direct tv dish, and Bryston 28 sst's monos for main.
When I connected this gear; everytime I simply touched the hdmi from sat to either my tv; or processor; I had a loud and bad 'hum'; thought maybe it was problem with sat. I had an electrician come out; installed a grounding rod into earth; and also fixed ground. Still had hum; then I realized when I used AEU balanced cables from VAC in cinema mode to Marantz; it created the hum and ground loop. Called VAC; they suggested I use rca ic's, but keep source selection as balanced to 'fool' the ground problem. I did that; and it eliminated 85% of hum, but not all of it. Hum only occurs when I switch the source on VAC from two channel into Cinema mode; otherwise on two channel music; system is completely quiet with no hum. I have three dedicated 20 amp lines.
Does anyone have any thoughts on how to eliminate remaining hum? I did borrow an Integra 80.2 to see if it was problem with Marantz; the Integra had significantly less hum; it may have different internal grounding or switching; also Marantz did send me out a replacement 7005, both units had same hum issues. Is there just bad synergy between VAC and Marantz, or can this be cured. Thanks for your thougths; I have gone thru many different solutions..but not there yet.
Happy Holidays and Thanks...
When I connected this gear; everytime I simply touched the hdmi from sat to either my tv; or processor; I had a loud and bad 'hum'; thought maybe it was problem with sat. I had an electrician come out; installed a grounding rod into earth; and also fixed ground. Still had hum; then I realized when I used AEU balanced cables from VAC in cinema mode to Marantz; it created the hum and ground loop. Called VAC; they suggested I use rca ic's, but keep source selection as balanced to 'fool' the ground problem. I did that; and it eliminated 85% of hum, but not all of it. Hum only occurs when I switch the source on VAC from two channel into Cinema mode; otherwise on two channel music; system is completely quiet with no hum. I have three dedicated 20 amp lines.
Does anyone have any thoughts on how to eliminate remaining hum? I did borrow an Integra 80.2 to see if it was problem with Marantz; the Integra had significantly less hum; it may have different internal grounding or switching; also Marantz did send me out a replacement 7005, both units had same hum issues. Is there just bad synergy between VAC and Marantz, or can this be cured. Thanks for your thougths; I have gone thru many different solutions..but not there yet.
Happy Holidays and Thanks...