I already have that connected for HT use and it makes no difference.
Yes you can either the Marantz or any other component with a ground lug including a line conditioner with one. If you are going to try to use the BHK amp with the REL’s speaker level you can also try connecting the REL’s LFE input to and “unused” input on the Marantz as this will provide and alternative ground.
Hi everyone,
Just received the ground kit from PS Audio. They were very responsive and i got the kit in my mailbox within a couple of days. Thanks guys!
Unfortunately, it did not work and the hum is still there when I switch the BHK250 to standby.
Also tried running the high level input earth wire to my marantz AVR phono earth and it also didn’t solve the problem.
This is really driving me nuts… 
I have the BHK Pre, two BHK 300 mono blocks, P20 regenerator and two REL T/9i’s. I too ordered and installed the PSA ground lugs and installed them in my mono blocks with the same result as you - the hum persists. I spoke with REL and they have a resistor network that they claim will resolve the hum issue but want $100 for the kit (I suspect I would need two). Before doing that, I plan to assign the two RELs to their own zone in the P20 and have that zone set to power down at the end of a listening session. Not the most elegant solution but it should be effective.
Thanks. I’ll touch base with them. I don’t mind paying $100 to fix the issue.
The REL resistor network and PSA ground lug) solved the hum issue for me with my S/5 SHO and BHK 250.
I wonder if the REL arrow wireless kit would work?
Normally I’d keep away from wireless stuff but reviews & all reports indicate it’s lossless quality.
Indeed, the REL wireless kits do solve the hum issue, and in my experience they have zero negative effect on sound quality. I use the older Longbow system to wirelessly connect two REL subs – very convenient. (Longbow is connected to my amp via the high-level input.) I would assume REL’s newer wireless products are equal or better, but I have no personal experience with them.
Quick update.
Bought an arrow wireless kit. Didn’t fix the issue.
I spoke to REL last Friday. They said if the subwoofer is humming all the time, the input circuit needs to be repaired. It’s basically been fried from being hooked up to a non-zero ground. It’s a simple repair, but they’ll need the sub in hand to do the repair.
Mine isnt humming all the time. Only when the BHK250 is in standby.
Got it. It sounds like you need the REL resistor network. $100 for a set of two for both channels.
Yep, thats the plan… Have ordered one and will hopefully have it in a few weeks.
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I have the same set up and needed to by the resistor kit from Rel. Worth the money.
ok, I have found a workaround (not fix)…
I am running the REL Sub into a port on my p12 which is set to to ‘power on / off’ with the unit - the others which have my DSD / BHK pre / BHK250 are set to always on.
I have connected the BHK pre trigger out to the P12 so when I switch the preamp off it immediately switches off the power to the sub which in turn stops it from humming.
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Got my REL resistor kit today. Pics attached.
Interesting that PS Audio & REL worked together on devleoping the solution but PS Audio don’t seem to directly reference it when people talk about the problem on here.
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I had to get the add on grounding terminal from PS Audio and the resistor network from REL Audio.
Yep, I got that as well. Didnt make any difference on its own. Hopefully this works. I am a bit nervous about connecting it up though… 
So here’s a question.
It’s all wired up but I’ve left the black wire on the high level input hanging / taped off. Should I secure it to the earth as well?
Thanks for the update - how long ago did you order it? I’ve been exchanging emails with Justin at REL trying to get one made/ordered for a few weeks now. Let us know if it effectively eliminates the hum. Thanks!