Budget amp that will give Magnepan 3.6Rs better depth of soundstage

You didn’t mention how far away your Maggies are from the front wall. In my experience with Maggies, they MUST be a minimum of 4 feet out to get optimum front to back imaging. Anything less and the soundstage will suffer and no amp is going to make it much better. While a lot of people say 3 feet out will work, they don’t fully open up until they’re out 4 feet or more. If you are unable to bring them out that far, diffusion and not absorption behind the speakers will help with imaging. Try pulling them out to 4 feet (if they’re not already) and toe them in slightly, before spending money on an amplifier.

The room would need addressing before considering more power, but a better amp can make some significant improvements to the presence, dynamics and stage. 
 

What about wood diffusion behind the speakers along the front wall and then on the first reflection points? I purchased some cheap and very effective BXI quadratic panels on Amazon that did amazing things for the imaging and stage depth. 
 

I’ve owned numerous Magnepan models spanning 40 years time, and currently use MG 20.7’s.

in this order:

6’ from rear wall (put them on casters with locking wheels if need be)

experiment with toe in-mms matter

cheap but great amps? Crown Pro series, carver sunfire, parasouund. Adcom

good listening!!!

I am currently running Magnepan 1.7i in an 11' x 14' room with two REL subs.

Speakers need to be 4'-5' from the front wall.  

I have used as little as 25 watts to 50 watts from a good tube amp.  Only bass was improved with big SS power.

For $750 or less, you are looking at older amps.  I had an ATI 1502 (225 watts @ 4 ohms) that did fine.  Look for high-current more than just a watt rating.  

Unfortunately, a lot of these older amps are due for service.  

Peachtree GaN 400 watts @ $ 2500 run my Maggies Beautifully.