Hi,
having some problems with the heat. I have a fmr compressor with a bass eq in the sidechain to not compress the life out of my kick& bass. this works nice. but when I put the heat before it in my master insert of my Mackie mixer I get ground hum. 
only fmr is fine. only heat is fine. both together = hum. you have any tips ? can’t use balanced cables because its insert. Using the the heat mainly with clean boost to gently warm up the Master buss.
Are you plugged into a grounded power outlet? Might help.
I just encountered a similar hum problem with my Analog Drive and Motu 896mk3 audio interface. Simply having the Motu turned on - even without any audio connections to anything - introduces a hum in the AD, that gets amplified by the distortion circuits. I think it got better when i rerouted my whole studio setup to a grounded wall outlet (should have done this ages ago anyway) but it s not completely gone.
Either the Motu is radiating EM that the AD picks up, or something is traveling through the powerline, though the AD psu is not grounded.
Are your Heat connected to usb? Could that be the reason?
Nope. Don’t use overbridge. I reorganized the studio so I can use shorter cables. It helped a bit. But I can still hear it on my headphones. Maybe I am just to sensitive ?
It´s the power supply of the Mackie that it picks up. When I connect only the AH its fine. Its the combination with the compressor. Even when I have it on bypass.
If both works by themselves then your not too sensitive.
I have never used the FMR compressor, but i remember reading something about problems regarding cabling them. Since they arent balanced, and if used with balanced gear you needed to make a special cable. But its been a while since ive read that. And since ive never owned one i didnt read it that thorough either so i migth be completely off here.
My AD is also plugged into a Mackie mixer (1642vlz4). Circuit Mono Station is plugged into the AD. Damn you ghostly electromagnetism 
With studio reorganization and short cables its now okayish. But not so happy with the noise floor and hum. 
I guess I have to live with it. Thanks guys !
When I encounter ground issues, two things I always check first are electricity and cabling. Are all your electric plugs connected to the same power strip? This should be the first step to check. Invest in a bigger power strip if you run out of socket spaces instead of using a secondary power strip, if at all possible. If you must use several power strips, make sure they all are connected from the same outlet point from the wall in order to minimize potential differences.
Second is checking that cable interfacing is correct. Use balanced interconnections where possible, and never use balanced interconnections with unbalanced gear. If your compressor does not have balanced i/o, use unbalanced cables to go into it and into the heat as well.
If neither of these solve the problem, you might need to invest into some ground lifter utilities, like DI boxes or galvanic isolators. Troubleshooting ground issues is a chore, but always pays off in the end.
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Thanks Tsutek,
that´s what i did. I disconencted all and had only the Mackie and the FMR/heat connected. I used a bit shorter cables and its okish now. I am looking strongly to the OTO boum because it gets too many boxes : FMR+Bass EQ pedal+Analog heat+DI-box vs one box of OTO Boum. Just not sure it will give me the results that I like (little Techno Pump/glue on the master and a slighty warm up on the highs like clean boost on the Heat.)
Try a ground loop isolater. They solved my gnd hums.
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