Stereo amps/stereo loop ground loop help

Hi guys, hoping you can help me! I've had my PBC10 board for a while now and it works great, but I'm trying to reduce the noise level when I'm not playing. I'm pretty sure it's a ground loop - is there any way I can test for this, and where would I need to put isolation boxes in my chain to remove it if it is a ground loop?

I'm not with the board right now, but I think these are the chains.

Guitar>wireless transmitter>wah>volume>PBC10 - split insert cable from out 6 - 7 to two amps (JVM410H and Victory V100)

then in loops 7 - 10 I'm running all stereo pedals other than an Eventide Rose, but I'm using the ring disconnect cables to convert that to stereo. A send and return comes from both amps into these pedals in stereo. I'm also running a TRS cable for amp switching to the Victory and a MIDI cable to the JVM for the same reason. Mono/Stereo buttons on the PBC are set to the right settings (I think) and I'm using the ISO B switch too.

Happy to make a diagram if that helps! When I'm not playing, especially with higher gain, there's a loud hum coming from the Victory which I'm assuming is a ground loop. Looking to test that then grab an EBTech hum eliminator (or two) to fix the problem. How would I test for ground loops, and where would I need to put the hum eliminator(s) in my chain for them to work?

Sorry for all the questions, I'm pretty new to all this stuff! Thank you.
 
THe way I would debug it is to start with the amp that's connected to Out B. Make sure Iso B is on, which should take care of any grounding issues on that connection. Since you've already done that, now unplug the cable from the loop send on that amp. If the noise doesn't go away, also try unplugging the cable from the input of that same amp. Hopefully, unplugging one or two of the cables will fix the issue. if that's the case, adding isolation transformers to that connection or connections should take care of it.

If that doesn't do it, you're going to need to keep unplugging things to find the culprit. Start stripping down the rig to the smallest configuration that still works - hopefully that's not noisy - then start adding things back in, one at a time.
 
Ah, wonderful, thank you! I'll try that and see if I can hunt it down.
Just to clarify, start with the B output that already has the isolator on it, and work from there? You mention the send cables, do I need to check the returns, and the MIDI/TRS switching cables too?
 
Because that first connection (Out B to return) is already isolated, you probably don't need to do anything with that. But, if you can't find any other problem, you may as well unplug that in the unlikely chance that it isn't properly isolated. Likewise the function switch and MIDI porta are also isolated, so they shouldn't need to be unplugged, but are worth trying if nothing else works.
 
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