Best speaker for the Spectral DMA 360 series 2 amp

I have no idea how Magneplanars would work in your room.

The Zu Defs are a little over $10k, while the JBL Synthesis and CARs are closer to $20k. The most cost effective solution would be to pick up a pair of vintage Altec VOTT type loudspeakers and refurb them. They are specifically designed to work in the large spaces. A decent condition used pair and the cost of refurbishment might run around $4k. There's a story in the current Stereophile about getting Altecs to work at their best.

Magnepan or dynamic speakers? There is a huge difference in presentation between these vastly different speaker types. This is one decision you should make before going forward.

For years Spectral teamed with Avalon Acoustics and MIT cable. I believe they called the system 2C3D or two channel three dimensional sound.

Of the speakers you mention, the Aerial is probably the most bass heavy. That may be the best match for your room. For your amp, though, you may want to consider some other options. Here's a few things that may work well with your amp and your room: Vandersteen 3's and a pair of their subs, Martin Logan Cls's and a pair of subs (I've heard them several times with Kinergetics Research subs and they sounded great but I don't know if they are still made), and a pair of Genesis (I forget the model but they were around $15000. They look like a pair of Watt/Puppies but they have powered subs. I heard them in a room like yours and they sounded very good.)

Thanks! I do like panels, imaging and sound staging are important as well. I heard the big Soundlabs once and was blown away. I really like the low level detail.
However it was in a small room compared to mine and I don't know how spectral would match up. I could change the amps if I need to.

I have heard the soundlabs, though with non-Spectral amplification and they sounded superb. The best system I have ever heard happened to be a fully Spectral /MIT syst in a moderately large room and Avalon Eidolons as the speakers. I run Spectral/MIT w/Eggleston Andras w/ very good results. Have you heard/ considered Egglestons before? Obviously your specific room will come into play, but, in my system at least, the andras plumb the depths w/ their dual 12" dynaudio drivers (+esotar tweeter) and can move some serious air, while managing to be pitch coherent, engaging and hollographic in my system, for what its worth. Happy listening and best of luck in your search.