+8 db is slightly less than 'double' from a hearing perspective. Likely cause is difference in speaker and room response if that is the sole change.
Why are the grounds commoned in the wall box for two circuits? If there are two circuits, the ground should ONLY tie at the buss panel bar.
I'm assuming two AC circuits and one amp on each.
Are you using balanced cables? If not, try them. The screen should only be connected at the pre amp end.
Start with just amp with back shorted inputs connected to speakers. If it is quiet, connect only preamp with nothing else. If still quiet, add one piece at a time until the noise appears, then deal with it.
Sadly Odyssey does not list amp gain. It would be possible to pad the amp input if dropping the gain 8db removed the noise, which I doubt.
I built studios in Los Angeles. I also fixed botched installs. ALL could play on STUN without any noise whatsoever. PM me if you wish to avoid the i......t, [e.g. DIMMERs don't hum, they buzz!] chatter here.
Why are the grounds commoned in the wall box for two circuits? If there are two circuits, the ground should ONLY tie at the buss panel bar.
I'm assuming two AC circuits and one amp on each.
Are you using balanced cables? If not, try them. The screen should only be connected at the pre amp end.
Start with just amp with back shorted inputs connected to speakers. If it is quiet, connect only preamp with nothing else. If still quiet, add one piece at a time until the noise appears, then deal with it.
Sadly Odyssey does not list amp gain. It would be possible to pad the amp input if dropping the gain 8db removed the noise, which I doubt.
I built studios in Los Angeles. I also fixed botched installs. ALL could play on STUN without any noise whatsoever. PM me if you wish to avoid the i......t, [e.g. DIMMERs don't hum, they buzz!] chatter here.