It sounds like that the Pass preamp is providing the signal ground that the Plinius "chassis/open ground" switch provides. So by opening the ground on the Plinius, you are eliminating multiple ground paths which caused the hums. Multiple paths remain along the signal path so floating the power cord ground doesn't help. Like it's stated above - it works, so enjoy.
Chassis ground and balanced mode - please help me
Plinius SA 102 has a ground switch (open vs. chassis) that they specify should be set to Chassis when running in balanced mode.
1. I assume that this has to do with achieving proper noise cancellation - but if not can someone straighten me out?
The problem: I am trying to run the Plinius with a Pass Labs X1 pre in balanced mode. There is a LOUD ground loop hum when ground is set to chassis that goes away in open position. Floating one of them does not help.
2. If I power the Plinius and the Pass using two separate lines back to my panel, will this ground loop problem be removed?
3. Will I be able to solve this problem?
1. I assume that this has to do with achieving proper noise cancellation - but if not can someone straighten me out?
The problem: I am trying to run the Plinius with a Pass Labs X1 pre in balanced mode. There is a LOUD ground loop hum when ground is set to chassis that goes away in open position. Floating one of them does not help.
2. If I power the Plinius and the Pass using two separate lines back to my panel, will this ground loop problem be removed?
3. Will I be able to solve this problem?