ReL Subs: High Level or Low Level connection

I have 2 RELs and I've tried both connections with a couple of different amps. High-level is the way to go IMO. 

That way the RELs are fed exactly the same signal as your mains rather than a filtered signal.

If you go with Speakon connections I highly recommend you upgrade the stock cables. Frank at Signal Cable makes a high quality custom cable  for around 1/2 the price of the REL Bassline Blue cables. 

I have two S/510.  For two channel, they are connected via high level with Analysis Plus wires.  I also do home theatre via a pass through on my preamp. I'm connected to the LFE input from my surround processor.  Seems to work well.

I want my mains to run full range for two channel. 

High level is what REL's designed for, and my experience this best. I've experimented and continue to experiment with high level cables, thus far stock, Duelund tin plated copper, always Neutrik connectors not the cheapo copies. Both stock and Duelund litz wire, next will be VH Audio UniCrystal Airlock, solid core wire. Also various configurations of hookup to my 300B monoblocks vs 845 stereo amps. Finally power cords.

So many variables, not to mention crossover and level on subs, almost forgot to include running on same dedicated circuit as amps with added outlet. Some complain about lack of adjustment with REL's, that's not me. I much prefer the REL's integration vs the low level with DSP I've tried with other subs designed for low level outs.

I connect using high level with Neutrik SpeakOn connectors which are recommended by REL, never look back.

sns "I much prefer the REL’s integration vs the low level with DSP I’ve tried with other subs designed for low level outs."

What make and model of third party DSP or the make and model subwoofer with onboard low level input processing did you try?

If those "other subs" low frequency were rated at -3dB how did you determine their position within your room?