How many subs?

I did a four subwoofer array in 2011. Two of the subwoofers, which I use today are equipped with fourteen onboard Auto and Manual subwoofer related parameters none of which is a delay. An older third subwoofer used nine parameters and the forth basic subwoofer was slaved by one of the newer subwoofers.

I positioned them in asymmetrical near corner locations within a vaulted ceiling open room. Playing the below 200 Hz Sweep Tone through the mains simultaneously and each subwoofer individually I ran the Auto Room Optimization which adjusts the subwoofer only.

I then played a very familiar Double Bass and Drums recording that I recorded and made some minor manual adjustments to taste and saved the results to the subwoofers preset  memory. The procedure took less than two hours to complete. The results were a stunning room lock and elimination on all the rooms bass modes. 

I'm a hack but I know what my Basses sound like. I've come to learn Optimization or DSP is for main speaker integration and not a panacea for improperly positioned subwoofers or poorly adjusted sub-bass speakers. 

I did find the HT receivers auto speaker distance delay very benificial until I rearranged the HT room, spacing the seven speakers equal distance from the listening position. 

As a Bassist I simply do not understand the benefit of delaying already long low frequency wavelengths. I still have my acoustic 360/361 which is another story altogether.

I had the big REL Studio III for a short time. You should understand that all REL products are simply sub-bass speakers Their -6dB roll off is so dramatic they simply do not excite a rooms bass modes which allows them to located most anywhere in a given room. 

I'd suggest that hunger for more your seeking can be found in most any -3dB actual subwoofer positioned precisely within the rooms multiple standing wave bass modes. Many manufactures provide quality phone support to assist in adjustments to your taste.

All the best. 

@bilateral  I don't think there is a standard for Digital Signal Processing. Its not the answer for you anyway.

I'm aware that some companies rely on matching their products to speaker brands. Of course this is absurd. Actual subwoofers are adjusted, not matched to the speakers. 

-6dB@20Hz is hardly, if any, 20Hz output at all. 

You're looking for that delicate extra low +2dB@20Hz feeling coming from many modern recordings. If a dealer did that matchmaking, demand a refund or a store credit toward some actual subwoofers. You'll be amazed.  Take care,

@bilateral  Considering your living arrangement concerns the -6dB sub-bass speaker suggestion is understandable...but no. 

A subwoofer with a modicum of frequency response control would be a far greater advantage while maintaining the ability to go low if or when the opportunity or circumstances change. Ultimately, a subwoofer with customizable presets would allow you situational flexibility and convenience. 

I purchased my first subwoofer in 1967. Living in wood framed and floored ranch homes most of my life and annoyed by the travel of those filtered bass frequencies. While my little studio is substantially treated the HT room isn't and only first reflections are lightly addressed in the two channel room. I'm not a fan of closed in treated rooms. 

My two twelve inch subwoofers rest on simple to build DIY dollies. I used these soft rubber plate casters attached to twelve layer Baltic Birch (any 3/4" plywood) followed by old Boogie board closed cell foam and topped with four inch heavy latex, foam store foam.            

https://www.castercity.com/product/5-super-soft-gray-soft-rubber-plate-swivel-caster-3/

Decoupling, suspending and the twelve inch hight increase required resetting their settings. The resulting improvement in bass presentation was very noticeable. Unknowingly, the transmission of resonant frequencies throughout the dwelling structure were stunningly reduced. No more rattling and buzzing, gone, except for preset #6.   

@bilateral  Just a thought.

Saturday January 11, I filled in on Bass at a benefit held in a medium sized hall. After the sound check I noticed the front of house equipment rack included a 1U spaced component called DBX Drive Rack (something). 

The tech had left after the check. He was still working after I left that evening so I was unable to question. 

I think it might be a more recent Auto EQ system for both stage and / or front of house EQ. Just how this would function using REL's preferred speaker/high level connection without also affecting the mains? 

Front of house or FOA sound is a whole other world of audio. You might want to get clarification as to what the intended use of this DBX Drive Rack model is designed to control. Don't give up on your low frequency reinforcement. 

@bilateral sorry to hear of your day.

Lighting! My untouched 1959 formica covered ranch house has hanging brass fixtures right out of the Jetson’s. Regardless of their mid century cool the homes lighting is a nightmare. I sure could use your chops.

You take care.