Moving from the Magnepan 3.6 to the 20.1

I've been enjoying my Magnepan 3.6's immensely since I picked up a used pair about six months ago. This has got me wondering just how good the 20.1's could really be. My room is probably large enough for the 20.1's; it's 17.5w x 26L x 9h.

Unfortunately my local dealer doesn't stock the 20'1's so I don't have easy access to a pair for serious auditioning.

Have you made this move? How much 'better' are the 20.1's than the 3.6's? Were they better? What stood-out between the two?
I have heard both back to back at a dealer demo. The 3.6 was on a Mcintosh 252 and the 20.1 was on Mcintosh 1000 watt mono blocks.

The 20.1 have a LOT more bass. They dig deep and have good output. The midrange is not as forward on the 20.1 and a little more laid back. The highs sounded the same to me. I actually really like the forwardness of the 3.6 midrange, it makes vocals standout.

The 20.1 are a big up grade in sound quality. But $13,000 is a lot to spend on Magnepans with their sub-pare build quality...
I moved "up" from the 3.6s to the 20.1s and like James63, I noticed way better bass and an overall fuller sound. They were purchased used for about $8,000 and I have never regretted the move. Your room should be plenty big enough to let them perform the way they should. Mine are driven by a pair of Krell fpb 350's and even with that, I think they could stand twice the power. Mye stands are, IMO, a requirement for getting the most out of Maggies.

Go for it - you won't be disappointed.
You might be using a different amp now but if you are still using the VTL MB-125, you can forget about the 20.1. They need a lot more current.
I would most likely buy a used pair. I'm with you on the power requirements; I only use my VTL 125 MB's for my Khorns (which I keep in the same room as the Magnepans. One nice thing about the Khorns is that they sit right in the corners, out of the way)...

For the 3.6's I picked-up a used NAD C 275BEE stereo amp; it is really very good, especially for the money! It puts out 150W continuous and has plenty of head-room for brief peaks up to 450W into 4ohms...probably not as good as a big Pass Labs, but it costs a lot less! Eventually I would like to get a big Pass, maybe a X250.5 or a X350.5 or maybe even a XA60.5... I have also heard that the Cary 500MB (1000 watts into 4 ohms) sound great with the Magnepans...
The NAD won't be enough. You need more. The best I have heard driving 3.6 is Classe CAM 350 monoblock. It has been discontinued. They sold for around $7,000 new so you should be able to find them used for less than half.

Now I think about it. You might be better off keeping the 3.6 and getting a new amp than moving to 20.1. Your 3.6 has been under-driven. You have not had a chance to hear what it can do yet.