Moving from the Magnepan 3.6 to the 20.1

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.

Well, that is one option I have been debating... not sure which I will do first, a better amp or a pair of 20.1's.... probably a better amp though, so that I can see what the 3.6's can really do...

The 3.6 midrange driver is larger than the 20.1, and IMO they have superior sound, discounting the lower bass response!

I do not care for having magnets on both sides, in the push-pull configuration.