REL subwoofer using only red cable not yellow per REL technical dept


I am using a pair of REL 5/SHO subwoofers for 2 channel application and find it mates well with my pass monoblocks and harbeth 40.2 speakers.

I called REL recently because only using minimum setting( 10 clicks ) for gain and crossover and whether newer 812 faster sub would allow me use higher crossover and gain. 

REL suggested first unplug yellow wire from speaker terminal and turn up sub gain as that might improve the bass integration ..

So far sounds promising....just wanted to let others know about this possibility although YMMV....

Would anyone know if there’s a hum using a single Pass Labs monoblock
with a single Rel Subwoofer via speakon connection? Rel Acoustics claims you need to connect 2 subs when using monoblocks.
Wow, this is great info.  I just returned a REL based on my experience with one click making too much of a difference.  For instance, 7 clicks wasn’t really audible, 8 clicks was too much.  I figured I had bought too much sub for my little totems.  I recently realized that there is a speaker / recommended sub section on RELS sight.

Yep, they have the "Subwoofer Finder" tool, and suggest what sub(s) to use, but don't mention anything in that tool about using monoblocks, they only ask what type of speakers. Lots of helpful information on that site, and it would be worthwhile reading some of it prior to making a purchase.
I was hoping someone like @karmapolice would be willing to disconnect one of his Rel subs from one of the monoblocks and report back if there is any hum (assuming he still has rel sub and pass labs monos), or anyone else for that matter. 
I sum the 2 positive leads from each of my 2 RELs together in a pair of AQ banana plugs, and the negative leads into 2 other bananas and stick ’em in the power amp. The RELs are used in mono with this configuration. The main speakers are spades in the same 5 way binding posts and they all fit and work perfectly...I built the REL cables from Canare 4S11 "star quad" (using 3 of the 4 wires in each cable) with angled Neutrik plugs from Liechtenstein.
@wolf_garcia - yes, I got that from their website:

Here they’re talking about "Balanced/Differential/Class D" connection.
When doing so, please combine red and yellow leads together to form a single composite “+” or “hot” conductor as shown in the diagram below. Do not connect the black wire to the output terminals. Instead connect it to a chassis bolt as shown below.

However, they go on to say:
We do not recommend use of a single REL with ANY brand of monoblock amplifier as it is possible to observe slight channel-to-channel dc offset that can result in mild oscillation. For any monoblock, we recommend use of stereo pairs of the appropriate model of REL sub.
I’ve read issues with some Macintosh monoblocks, and I’m asking specifically about Pass Labs monoblocks with regards to connecting a single Rel sub to one of the monoblocks (using high level connection into sub).