The 11MS is a decent physical size but it would be great to have more of them to move more air for less excursion. How do I go about wiring up multiple speakers in a series-parallel arrangement so the Proprius can drive them and each speaker driver sounds the same individually? Would I be able to increase bass output with more drivers if I EQ other regions of the audible range down?

EQing an "unrestricted" (no box) single suspension speaker array to a roughly flat response at close proximity should easily replace headphone listening. Proprius dials at 9-10 o'clock and Majestic dial up high should make speaker hiss insignificant. I am open to the idea of more than one pair of Proprius and more than one Majestic DAC.

On the single existing driver, bass EQ might increase the extension a little, and with nearfield listening there is a little power and excursion available to spend on this. But the 11MS is not intended for high power handling or excursion, so moderate volumes only, and getting down to the 30s is going to be a significant ask.

Sticking with the same driver, the best bass results are going to come from loading it appropriately for bass, but then we're into reasonable size cabinets, loss of the open baffle qualities, and probably loss of the ability to use it on a desktop.

So I'd be tempted to try adding a small, well-integrated active subwoofer. The single-driver open baffle qualities will remain and flat extension to the high 20s should be possible, and the electrical adjustments already available on the subwoofer will prove invaluable in achieving good integration.

EDIT - they seem to be called gooseneck stands, like what they do for microphone positioning. Would be great to have it thick/hollow enough to thread a Spatia cable through it hmm.

First try

https://amcoustics.com/tools/amroc?l=12&w=9.75&h=7.5&ft=true&r60=0.6 - https://amcoustics.com/tools/amroc?l=12&w=9.75&h=7.5&ft=true&r60=0.6

Which is the acoustics of my workshop/listening room, paying attention to Bonello and Bolt-area.

Enter your own room dimensions (feet being easier than centimetres), and look at Bonello and Bolt-area again.

Also look at concentrations around 125Hz and 250Hz, and go to the "more about room modes and this calculator" link.

Because, if you find your room is awkward, I think you'll be at it forever and always dissatisfied.

As your music is all in digital files, a software graphic EQ would be the best way to go IMO.

I mainly want to correct the 11MS driver's mechanical response. Slightly raise the response between 6-7K, attenuate the response slightly at 8K, raise the response at the 350Hz dip, shelf down the 100-300Hz upper bass and reshape the bass section to get the result more flat. Will use a second 11MS purely for bass support. Well I might have two to four 11MS drivers for bass support actually. Open baffle or minimum enclosure. Close proximity. Will beat MySphere then I can sell it.

They do need some space to breathe though. They are not open baffle, but they certainly do sound staging.

I remember reading about them some time ago but there was not any review on the sound quality.

https://www.hifinews.com/content/duevel-venus-loudspeaker - https://www.hifinews.com/content/duevel-venus-loudspeaker

Say I want to increase my one driver per channel to four identical drivers per channel in a packed square arrangement on each side with a series-parallel wiring to keep the same driving impedance, what else electrically will change? I don't understand all the damping factor and inductance stuff. Discussion with Heinz Renner suggested there will be a loss of impulse response too...

And unless you are at the focal point with same length paths there will be some phase cancellations. You are using full range drivers so they will be putting short wavelength sounds but be a long way apart relative to wavelengths. You could align them on a baffle that curved or stepped towards you at the top and bottom I suppose.

What will 5 drivers give you, that one driver won’t for near field listening?

You would probably be better of with a different drive unit, in a different open baffle?

For the cost of ten 11ms drivers, I am sure you could find something better suited for an o/b speaker.

If you want to feel the low end, then there is no replacement for displacement.

The 11ms is just not going to cut it, and all bass drivers are not slow. You just need to find the right one.

Incidentally, I've had really great results with the sealed boxes in my second system and quite serious levels of digital EQ (+10db) below rolloff (20hz-30hz in this case). But the sealed boxes in question have 12" bass drivers, the amp has 220w/chan and I listen at moderate levels, so there is plenty of unused voice-coil heating and cone excursion to exploit! I'm also using digital PEQ to tame some room and cabinet resonances. It shouldn't work as well as it does. I can switch in and out instantly for comparisons, and with no EQ they just sound like the lovely 1970's speakers that they are, enjoyable but not truly realistic. But with EQ they keep the nice midrange/treble but most of the mush disappears from the mid/high bass and true low-end extension arrives. They sound "big" and impressive, and the midrange has hugely increased clarity - a very welcome effect which I find always happens when the mid/high bass is tamed.