BHK Pre and Power on the Way - REL Subwoofer Question

Paul McGowan said

Sorry about that. I’ll pass this on to John Hunter. I am sorry it didn’t work. Let me scratch our heads with this and find a solution.

Adding the REL is exactly the right thing to do from a sonic standpoint.

Allan, Still scratching our collective heads on this one for now.


Just a wild hair off the cuff thought…

With a bridged output, would it be a reasonable idea to create a virtual ground on a bridged amp by putting a couple of resistors across the output and tapping the middle for a virtual ground? Maybe two 2K 1/2W resistors?

Sp+ – 2K – (VG) – 2K – Sp-

Not sure exactly what values would be better, but two 2K 1/2W resistors in series should at least survive maximum output voltage levels (if I did my math right).

Of course, this is a theoretical exercise and not an “audiophile” solution. I am just throwing it out there for discussion and entertainment value. :slight_smile:




First off, connecting the BLACK wire of he REL high level cable would make the virtual ground equal to earth ground.

Not a big deal, and I suppose that the BHK outputs would not mind seeing a 2K load to earth given speaker load.

The REL will still hum when the BHK goes to standby because the + and -outputs get lifted and the REL high level connection is left hanging.




But would it still hum? The sub high level inputs would now be pulled to ground via the 2K resistors when the amp outputs are not driven. Would that be too high an impedance to silence the sub with no other input? If so, how high could you go with the virtual ground resistors - 5K, 10K? What is the input impedance of the high level inputs? I speculate that it is at least moderately high in order to present an entirely innocuous load to any reasonable amp/speaker pairing.



The REL will still hum.

2K is too far away from ground for the + inputs.

Ideally, the - input of the REL would be connected to signal ground or within 100 ohms of signal ground.



I installed the “grounding” kit yesterday. It was sent by PS Audio (thank you). Unfortunately, it doesn’t fix the hum. Since I have a P10 now, all I need to do is cut off power to the outlet where I connected the subs. Without the P10, it was a hassle switching the subs off individually.


Same problem with Stellar M700s, right? I have an REL sub I’d like to use with them but am wary of grounding issues. If the black wire on the REL cable is soldered to the outside of an RCA jack, can it be grounded through an output RCA in the preamp?


Most sub amps do not like to be connected to Class D amps because of grounding issues but you still have the option of using the RCA inputs on the REL.


I have the BHK-250 with the grounding kit and a REL S/5 and I use the 12 volt trigger to turn the amp on and off. I only get the hum for about 20 seconds when the amp is turned on (via the trigger), and again when it is turned off. That way I don’t have to turn the sub off.


Right. Connect the RELs as instructed for a balanced output and you’ll be fine.


Hi, I’m new to the forum. Paul, first let me say that I’m very impressed with the customer-centricity of your operation, which is all too rare in the hi-fi market and the larger consumer market in general. You really are on the right track. I was not surprised when you recently mentioned that Seth Godin is a good friend. His influence is very much evident in your approach to customer engagement, social media, YouTube videos, and this forum.

Now, on to the heart of the matter. I will take shipment of my new BHK-250 and Signature Pre on Monday, which I am very excited about. I’m also very interested in incorporating a pair of Subwoofers into my system. While I’m not completely new to the hobby, it’s been nearly 20 years since I was last seriously involved. REL subwoofers seem to be one of the few pieces of gear that get a consensus rave from all the insider experts I have heard from or whose opinions I have read online. The secret sauce seems to be their musicality and their unique set-up using the amps binding posts rather than through the traditional set-up through the pre-amp. In this regard, I was discouraged and then heartened when I read through this thread. I really like that you are willing to be transparent and let us “backstage” into the workshop where trial-and-error and tinkering takes place in the pursuit of troubleshooting and innovation.

However, as I kept reading my discouragement returned. Seems that you may have lost the impetus to find a solution to this problem. I am inspired by your pursuit of “perfection” in all things audio, so this seeming abdication is not consistent with your brand promise. As strong b-2-b partners it seems that both PS Audio and REL share a mutual interest in having your amps and their subs integrate in a seamless manner. Why should we accept compromise here?

Today, I called your customer service line to get clarification on the matter (and to get a resolution to a web bug that was not allowing me to register to your forum–BTW the location of the change password link is not intuitive on your website). I spoke with Jeremy. He was cordial, but instructed me to use the pre-amp to connect the REL subs. I mentioned that this is not the preferred method I’ve seen online, but he didn’t seem to know or care about this. As a definite “beginner” to hi-end audio, I found this confusing and a bit off-putting. Sort of the situation when an average consumer takes their car to the local garage and the mechanic overwhelms them with technical jargon. From a customer experience point of view (which is my professional expertise), it’s less than ideal.

So let me conclude by asking a few pointed questions:

  1. Do you have plans to create a true solution to this BHK/REL connection issue?

  2. From a sonic perspective, how much of a compromise is it to connect the REL to a pre-amp rather than the amp as REL suggests?

  3. Are there other worthy subwoofer brands (such as SVS, who like PS Audio seem to be quite customer-centric, with free home trials, as well as rave reviews on their gear) worth considering to avoid the hassle of dealing with the hum issue?

Thanks so much and keep up the good work!



I apologize. No one should ever feel put off by a member of our staff. Maybe Jeremy was having “one of those days” as it happens to us all. I’ve definitely reached out to him about it and thank you for the feedback. We can all use it.

RELs definitely like to be connected to the amplifier’s output. It’s what we did at the RMAF and it works flawlessly. The only issues come in when the BHK amps go in standby. Then, there can be a small amount of hum from the REL when it is disconnected, something easily remedied with the addition of a ground wire. I can help or Jeremy can as well.

This is the preferred method.

Sevilla said

I installed the “grounding” kit yesterday. It was sent by PS Audio (thank you). Unfortunately, it doesn’t fix the hum. Since I have a P10 now, all I need to do is cut off power to the outlet where I connected the subs. Without the P10, it was a hassle switching the subs off individually.

I am quoting myself above from May 10, 2017. The grounding kit never worked in my system. This might not be helpful to wakethetown, but I’ll share anyway. I have my two REL subs connected to the P10 along with the rest of my equipment. Power to the subs gets cut off first, so by the time my BHK 250 goes into power save mode, everything is dead silent.

I do agree with wakethetown in expecting a true solution to this issue. Re-reading this post reminded me of my surprise to find out the BHK amps didn’t have grounding posts. I had a McIntosh integrated amp with grounding post, before my BHK 250, and my subs never hummed then. I didn’t have this amazing sound quality either, but that’s another story.

By the way, I did tech support in my younger days, and although I don’t excuse any lapse in service quality, I know how difficult it can be some days. Paul and crew have always gone above and beyond in my experience.



Take a look at the Rythmik subs as they work great with the speaker level inputs from the binding posts of the BHK 250. I have a pair in both systems and find them better than the REL subs I had in the past. Smaller company with headquarters in Austin, TX. with great customer service from the owner and the sales manager either by phone or e-mail. Bonus is that they are a good bit cheaper than REL as you are buying direct from the company like HSU and SVS.


Hi Paul, thanks for your quick reply and for your offer to assist me in setting up the RELs. I appreciate your hearing my feedback about the customer support I received. I understand that it’s very hard to be on our “best game” at all times.

If I can follow up, I am interested to get your perspective on what may have changed between your statement in April (“Sorry about that. I’ll pass this on to John Hunter. I am sorry it didn’t work. Let me scratch our heads with this and find a solution.”) and now. As Sevilla states, the grounding kit “didn’t fix the hum.” Perhaps, you could add an instructional video showing us how to correctly install the grounding kit, hook up the RELs, and what the small hum actually sounds like.

Sevilla, thanks for your follow-up post as well. I reached out to Rythmik, and received a prompt reply from one of their tech supports: “Our A370PEQ, A370PEQ3 and H600PEQ3 amps have speaker level inputs. Models like the F12, E15HP, F15HP and FV15HP come with those amps. Contrary to REL recommendation, we do recommend using RCA or XLR inputs in first place and speaker level inputs just as a last option. Speaker level inputs can introduce coloration to the sound from the amplifier.

It’s all a bit confusing, especially to a relative “newbie” like me. Powered subwoofers have amps, so whose going to be the “transparent” component and who is the one who adds “color”? These components do not stand alone, so they need to work together.




Many prefer using speaker level inputs because the subwoofers receiving exactly the same signal the main speakers receive. This insures the timing, frequency response, phase, etc. (“coloration”) is precisely the same. This can provide better subwoofer integration with the main speakers.

Others like using the signal from the preamp.

Both work. Try them and see which you prefer.


Right. We’ve done this on a regular basis with the RELs, our grounding kit, and BHK without a problem.

The Rythmik response is hilarious. They get it, but don’t like it. They are correct. In fact, it is the colorations of the amplifier we are after!


I spent over 15 years using a pair of Vandersteen 2WQ’s where speaker level input is the only option so using that method with the Rythmik’s was second nature to me. I did in fact try it both ways as Brian and Enrique suggested but still preferred the speaker level inputs. So by all means try it both ways with whichever brand you choose. High dollar cables are not needed for either method. Using the second set of outputs on the amp does however keep all the cables going to the subs at the same level making routing easier. Also keeps the level to everything on the speaker end the same allowing for easier matching. If using line level you will have to account for the pretty significant difference between the gain levels of the RCA and XLR preamp outputs.


Just received my BHK 250 and Signature Preamp. Transported to another level! :slight_smile: Really sublime. I came up with this: “costs almost as much as a car, but takes you a lot further without leaving the comfort of your chair.” What a treat!!!

Thanks for all who have added their perspective. I have a very basic question (dare I say, “stupid”): when using speaker level input on the BHK amp would I use the same speaker terminals as I’m using for my main speakers or would I use the bi-wire terminals?

I look forward to experimenting with this when I get my subs. For the time being, I’m just relishing the beautiful, detailed music. . .



p.s. how does one add the footer with one’s equipment set-up?



It works either way with the terminals and I have tried both. If both sets of cables are bananas or spades it’s easier to use both sets as signal is the same. If one pair of each then you can use a single pair.