wyred 500st mk11 and rel sub r528

Connecting the red and yellow wires to the amps positive speaker posts is a high level input for the Rel. Not sure why they suggested using the lfe for ground. I have heard of problems with differential amps and/or class d. I had no problem with my Bryston B100 (uses differential amps) and my Aavik U300 (class d) and connecting the black wire to either negative speaker post. But I also have a Rel B3.

As with many REL subs, the manual for the R528 (see page 6, pdf page 7) suggests connecting the black wire to a chassis screw on the amp when connecting at speaker-level to an amp having balanced (or bridged) outputs, assuming the amp does not provide a suitable circuit ground connection point on its rear panel.

Many people do that, and in most cases it will work fine. Depending on the internal grounding configuration of the amp, however, there is a possibility that a large hum could result. So if you try that, when powering up for the first time be sure to have the sub's volume control turned down, and bring it up slowly.

I am not sufficiently familiar with your Oppo, and how or if it is connected to the amp, to be able to comment on the suggestion of providing the REL with a ground via an LFE connection.

In any event, though, if connecting the black wire to a chassis screw is not feasible or does not work satisfactorily, an excellent approach would be to solder the black wire to the ground sleeve connection point of an RCA plug, connecting nothing to the center pin of the plug. If you are connecting the amp's inputs via XLR, then simply insert that plug into one of its unused RCA connectors. If you are connecting the amp's inputs via those RCA connectors, use an adapter such as this one to implement that connection.

I would strongly recommend that you do NOT make the common mistake, in the case of amps having balanced or bridged outputs, of connecting the black wire to a negative output terminal of the amp. Depending on the internal grounding configuration of both the amp and the sub, that creates at least a slight possibility of damaging the amp. And even if doing that appears to work satisfactorily, as in Xti16's case, it is not ideal from a sonic standpoint if only one sub is being used. What would happen in that situation is that instead of the input circuit of the sub summing the signals for the two channels together, it would give approximately 10 db more emphasis to the channel to which the black wire is connected than to the other channel, according to my calculations.

Regards,
-- Al

HI Al
The Oppo has dedicated RCA and XLR outputs for two channel play back via a 32bit Dac which I am using for my front mains and they go too my w4s amp. I have a 5 channel B&K amp for center and rear surround speakers. The Oppo also has outputs for FL,FR,SR,SL,RR.RL,SW for those people who only want the player for hometheater use. I got the w4s amp because it had balanced inputs and the B&K didn't. Rel said because I had the .1lfe connected that it would act as a ground for the sub and to not connect the Black wire on the speakeon wire only the Red and Yellow to the left and right positive leads on the w4s. I really want to keep the Rel in my set-up because my Sonus Faber Pianos need that extra boost in the mid area they just sound fuller. The manual also shows connecting the Rel via the Low-Level input, but I'm not clear on where to connect on the Oppo or if it is going to do the same as the speakeron.

Mike