This is a great question:
technically if you have positioning problems due to a hostile environment or barriers caused by furniture or wives, the compromise of an ethereal cable could make sense.
But with excellent AQ cable from 5 meters, you could still find a valid compromise in the positioning of the Sub.
I hope the meme didn’t offend you.
I live in Rome and also had the opportunity to see two Christmas celebrations with Pope John Paul II and Francis in person.
There are a few users who used to be here who have six subs but not in two stacks. They put them in various places around the room. I guess it sounds better and annoys the cat.
For the record of those who follow this thread, I’m also considering listening to a Sonus Faber Gravis VI.
Long story short, a subwoofer similar to the M&K Sound, but made in Italy with class AB amplification and an extra luxury cabinet covered in leather and real lacquered wood essence.
I listened to the Sonus Faber:
damn, we are at really high levels. 
It was connected via HIGH-LEVEL and integrated perfectly into the McIntosh, Sonus Faber system.
Construction that borders on perfection and the same principle as the double non-isobaric push-pull woofer of M&K Sound.
Considering its price and the applicable discounts, I could purchase 2 of them in the future.
Gentlemen, now I only have to listen to the REL, but:
a single No.31 will never be able to compete (considering the cost) with two Magico A-SUBs or 2 Gravis VIs.
I’ll keep you up-to-date.
Single subs is just wrong. If you can’t do two don’t bother. Oh sure, a few people are convinced it’s just fine but so are $100 cables. For some. Not you.
So, better a No. 31, to start with, than two SF/Magico? 
Did I get it right?
It’s true.
You raised a doubt of mine, I’ll explain:
to connect a subwoofer, not via High-Level, would it make sense to invest significant sums compared to a “simple” AQ Wolf XLR?
That is, to an XLR signal cable and not to a specialized one (therefore cheaper in materials) for low frequencies only.
I was thinking of switching to a Neotech “The Sahara-ITX” which unfortunately costs a lot.
I exclude “The Amazon-ITX” for the sub because it is made of silver and, I think, wasted on low frequencies.
What do you think about it?
Don’t talk to Al about cables, it’s soooo dangerous!!!
Here… I imagined well then…
With REL subs, very expensive cable options exist. I went with the most expensive cables Syn Research makes. They list for $2750. each. Do they improve the sound dramatically? Sadly, yes.
Which audio device is fine with a low cost cable? I haven’t found it yet.
If you buy other than REL, I think you will encounter the same madness.
I will say I have gone with stock cables in the past for subs, thinking how much difference could it make. I lived that way for a long time. But as always, better cables allow for better sound.
“So, better a No. 31, to start with, than two SF/Magico?
Did I get it right?”
If you plan to buy a second N31 one of these days. I haven’t any experience with Magico subs so I am useless to you there.
Well, less for my pocket, but I had understood that when they “packaged” the specific cable for low frequencies we were faced with a huge compromise.
Unfortunately, I will start by purchasing a first subwoofer, to test it in my environment, and after a few months, I will be able to add a second.
I will make this “crazy” purchase by next June.
Ah, The Amazon (UP-OCC rectangular solid-state silver) costs even more…
Speed/size ratio is not actually a thing. Subjective subwoofer driver speed isn’t a function of diameter, though this is a commonly held belief/misconception.
It’s actually related to the frequency response (LF damping) and inductance of the system. It can be true that larger drivers have larger, higher inductance coil and motor designs or peakiness in their LF alignment (with at higher levels), but this is one of those “correlation isn’t causality” things. Larger subs can sound equally fat and musical and have the benefit of much lower distortion (all other things being equal) because displacement for a given SPL is lower.
Other than that, I do like a number of aspects of your comparison. Thanks for sharing it!
I have worked at a number of companies and, typically, customers do not want horizontally opposed subwoofer drivers. While it’s pretty easy to make a stiff, small box without exotic materials and place the first panel modes well above the band of the subwoofer, a reduction in enclosure vibration is a good thing.
However, there is a lot of confusion around it. Even though subwoofers are omnidirectional, people wonder if the side firing drivers can be placed near a wall (they can) or if that will hurt the sound (it won’t, other than the expected placement/room mode changes). KEF (among others) has continued to push it.
The other knock against it is that you can build a better, bigger woofer for less cost that two smaller woofers (of the same output/displacement), so the value proposition is worse for the dual driver configuration.
100% agree on the RELS and the Syn Research took the subs to another level allowed me to dial them in a lot easier as well … now don’t forget those power cables feeding them 
I use Stealth power cables.
Audience 24 se-i HP for me only because they where in the cupboard … but they do make a difference as well
Never thought I’d be in the dual sub family for Hi-fi but once you go down the path and hear the difference you know they are never coming out … played with Gravis and a couple of others but the Rels just sound great
Good fun😀
I use a REL Air Ship transmitter on one of my REL Carbon Specials. It recently stopped working so I hardwired that sub pending repair / replacement. I didn’t notice any difference one way or the other…
I’m waiting on an Atmosphere SX Rel Spec Reference cable I ordered from Juan…
Where is Steven? He’s the self-appointed world expert on subs!
