REL Hum. Stumped

I’m getting a hum from both my REL subs. The strange thing is the subs don’t even need to be connected to the Luxman integrated to hum. All I have to do to get them to hum is plug in the Speakon connector.  If I disconnect the Speakon at the sub the hum stops. 

Connecting the high level wires at the amp doesn’t stop the hum;

nor does connecting the black wire to the amps grounding lug.

nor does running an RCA from an input on amp to the unused LFE input on sub

nor does using HumX to lift the ground

nor does changing outlets

nor does using the same outlet as the amp

nor does using a isolation transformer 


Btw the amp doesn’t even have to plugged in and I get the hum!

Im lost, any thoughts on what I should try next. 


Please don't use a cheater plug for extended use. The work as a trouble shooting tool but are dangerous if there is a short. They are designed to provide a ground on an old two wire house not lift the ground of a three wire system.

I had the same experience with REL high level connections,  whether a single sub or two subs. The hum was only apparent when no music was being, but still annoying. I then purchased a KEF KC62 and connected left and right channels from my preamp out jacks. No hum and more bass to boot.

Alas, I too have the hum with my pair of S/812s.  Amplifier is pure balanced, BAT VK655se, which apparently presents its own unique issues with the Rel Speakon.  

@last_lemming  I am completely ignorant of technology, so I'll never be able to reproduce what you did.   Did you shield/replace the subs original power cables??  Is there a version on the market of what you built yourself?   

Thanks.  Most frustrating, but I'm not giving up (yet), as the direct-to-amp Rel makes exquisite music, etc.