$165k - $200k speaker performance for $40k ?

Why add any sub? Does statement sound, whatever it is, require high volume ultra deep bass, or is it just exceptional sound?

No loudspeaker is perfect, but the Mag 20.7 sets very high standards for a moderate amount of audiophile money.

In my experience the deepest bass provides significant benefits in imaging/soundstaging in addition to reproducing the lowest frequencies, so I guess I may differ from Onhwy61 on this. The cost-no-object designs provide this foundation so I think Mitch is correct in incorporating multiple subs into this exercise.

Also in my experience, where the cost-no-object designs really set themselves apart is in terms of scale, dynamics, and ultimate physical presence of the performers and performance (along with ultimate refinement, but I think that's not quite as big a deal on an absolute basis relative to the other issues if you're starting with $40k speakers). While the Maggies can probably match the scale, dynamically they're different from cone-derived speakers so not sure adding subs will get you all the way there. Some may actually prefer the Maggies, but it's still different.

To create the presence and scale of the models you list in a room that size I believe is just going to require a lot of high-quality drivers in a large cabinet to move enough air from the upper bass on up -- at some point size matters (although I think the subs can match or maybe even surpass them on the bottom end). This precludes a lot of great speakers (i.e. Sasha, Pearl, Vandy Model 7, etc.) from contention, although I'm sure they'd sound fantastic with 2 or 4 high-quality subs properly integrated. You're specifically asking to match the larger benchmarks, and not sure they could produce the dynamics and scale to absolutely match them.

My best shot at it would be to take some of the smaller siblings of the best cost-no-object models and add some subs. I'm thinking speakers like Magico Q3, Rockport Avior, Vivid Giya G2 (a little over budget unless buying used), etc. My guess is this still won't quite do it but could get you tantalizingly close. And the extra $120k to $160k in your bank account might help cushion the blow that you maybe didn't quite get there.

This was fun to think about and can't wait to see what others come up with. Best of luck.

In theory, adding multiple powered subs to any good quality full range speaker is one way to tackle optimizing performance in a larger room and making a "statement" accordingly, possibly even a bigger more impressive "statement" than the ones from others that you are targeting to emulate.

The thing I would question more is the planars ability to sound like conventional dynamic designs or vice versa in this case, mainly in terms of large scale mid to upper bass macro-dynamics that blend in well with the lower bass of the dynamic subs. The "statement" should still be quite impressive, but I would expect the resulting sound to be a somewhat different flavor due to the basic design and physics of planars versus dynamic speakers.

After that, what can substitute for what and how much it costs becomes more of a subjective matter of what it takes to get system A to sound like system B. At this point its no longer just about speakers, but overall system synergy and sound.

I have thought about this for some time. I would answer "yes" to your question, provided you like planar speaker sound. And remember you would need a lot of power for those Magnepans.

I disagree with Mapman regarding subs. A pair of big REL G1s or MJ Acoustics 800s will blend well with planars. Just connect them at speaker level (JL Audio subs can't), at their lowest frequency, and don't be tempted to go high on the volume (so you won't notice them). The improvement in soundstaging and ambience are immense, as Soix says, as well as musical foundation, most of which you will feel more than hear. JL subs can't be connected at speaker level and their lowest frequency is 30Hz.

I disagree with Soix's idea of small speakers for such a huge volume.

A very different take on the problem (cheap brute force, a typical American solution to almost everything) would be a pair of GR Research LS9 speakers, now built and sold by Angel City Audio in California. I listened to a pair long time ago and they were impressive in both looks and sound. No need for subwoofers, for sure, and all the soundstage width, depth and height you would want with more bass depth and impact than almost anything.