When is a Listening Room Too Big

Some of the very best sound I've heard involved large systems playing in very large rooms. One setup was a dedicated listening room that was about 27' x 50' x 12' or so (just guessing) with a massive horn-based system. The other was a system using three Wilson MAXX 2s and two WP-7 in a pretty large conference room (at CES). I have also been impressed by a quite small system (YG Carmel) playing in a quite large ballroom. The space helps very much in giving the presentation proper scale. Wide spacing of the speakers also makes it possible for more than one person to be located in a sweet spot (in almost all typical home setups, the sweet spot is really far less than one foot wide).

With something like a Maggie 20.7, there might be some restriction on size if one wants to listen at high volume because of the amount of power that would be needed and the possible limitations on the speaker delivering high level of bass. But, I bet that at reasonable levels, Maggies would sound great in a large room (I have only heard them in a room of about 16' x 25'). Just a guess, but your hypothetical big room would not be too large and would be great for delivering realistic size to the soundstage.

You are right about sometimes less being more, especially in the case of a very lively larger room.

I think large rooms work well with Maggie in particular. The best Maggie setup I ever heard (and among the best I have heard anywhere) was at Jim SMith's Audition shop in Birmingham AL. SHowroom was large, but not huge. The panels were positioned almost in the middle of the room with lots of space behind and slightly more in front. I was blown away and bought a pair right then and there and had them for years until I moved into my current home where my room is fairly large but L shaped and narrow and optimal placement was a problem.

A sub or two or four can always be added if needed, but I suspect the other charms possible in a large room has a good chance to float the boat alone.

I tend to think of most peoples rooms as the main bottleneck with MAgnepan speakers. Most are not large enough to really let them be set up optimally and shine.

Yes you will likely want a good bit of power and maybe even a fairly beefy tube amp to drive them to higher volumes in most larger rooms though, if that is something that matters.

My advise is don't tailor the space specifically to your Maggie's, unless you are sure you are going to die with them. I would look for general dimensions that would work well with most medium to large speakers in case you have to upgrade from your Maggies someday.