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

Too much speaker for too little a room.  Knock out a couple of walls.  

I agree that those speakers are too big for the room. I would move down to 1.7’s. Which are excellent.

A used Schiit Vidar can be found in the $600 range.

I had Maggie 3.6Rs on loan for close to 20 days in a 12’ x 16’ room with a 220 wpc dual mono solid state amp with 75amps of current. A capable amp.. The room was the limiting factor. Just did not work very well at all. Sound stage was all wrong.

Same day of evaluation, swapped in a friends pair of much smaller pair of Maggie SMG-Cs just for grins (at his suggestion) and it was drastically better. It was a quick lesson in room acoustics and speaker response. Needed a much bigger room in retrospect. 

OP, I have been running Maggie 1.7i's with a Parasound A21+ , and a PrimaLuna Evo 300 preamp in a open plan room of 20 x 30ft., 9ft ceiling. The right side of the room is open to the front of the house, with only a staircase in-between the two large rooms.  The Parasound, (400w into 4ohms) completely pressurizes this space with the Maggies.  I play everything: jazz, classical, rock. I was just listening to "Kid A" by Radiohead, (Tidal MQA).  It was holographic in this space. A good friend is into blu-ray surround music (I cannot do it), and I sat him in the sweet spot. He was dumbfounded by the soundstage that expanded to the sides and overhead.  I use two Martin Login subs as well. But the Parasound is the heart and soul of the system.  Give it a listen with your bigger Maggies...I'm sure it won't disappoint. Oh, room acoustics: I have a large, deep sectional in the middle of the listening space and a large area rug underneath that, about 1.5ft in front of the Maggies.  That's it. My sound meter reads 30db avg. for pre-music sound, 25db when no one else is home.  My average listening is around 75 - 90db