Two or More Subwoofers?

Sounds like you will listen from a fixed position, and I'll assume you mostly listen alone. Hence the Geddes approach probably has rather low value to you.

Then it's a matter of SPL and impact. I would wait until you are in your new room, play around with layout enough, then decide if you need more subwoofer power.

BTW, it might be worth looking into DSP alternatives for the best subwoofer integration and room correction. Something as simple (albeit limited) as the DSSpeaker products (Antimode and such), going all the way to more complex solutions. My only source these days is an optimized computer, so I'm biased towards software solutions, but other options are available.

In my book, with my bias, my 2 cents:
1) get into your new room, optimize layout
2) work on room treatments
3) time-align subwwofer to 20.7 and do room correction maybe only to the subwoofers
4) maybe you need more subwoofer power

cheers

I have never heard of altitude affecting speaker performance. I was mile
high way back in grad school and things sound pretty good at RMAF - are
they rocky mountain high on altitude steroids?

. I know it takes a higher temperature to boil water. Is this a planer thing?

Not sure, but a Magnepan has a considerable amount of panel surface area, especially the bass panels which are probably 75% of the total area. Being over 5,000 ft higher in the Denver area I assume that the density of air is lower meaning that it is less work overall for the amps to move the panels; but I'm no physicist!

Thanks Stickman

Envious of your current and future room

I have a 15x27 room and that extra 3 feet would really be ideal.

What area of the foothills are you in?

Castle Rock