Best Cheap Amps for Magneplanar Speakers

If you are truly looking for a cheap amp....
$400,  I like the Old Sumo Andromeda II or III...(III might be $500)
$900,  I like the Muse Model One Hundred Sixty
These will both make maggies sing

I don't know what you call cheap, but I have had $300 qsc 1450 behind mmgs, and it put out clean, undistorted sound at concert level.  The lights in the house were dimming with pounding bass drums. I had an adcom preamp between source and qsc.  Mmgs were without fuse and sounding good, and the qsc was not even at 1/2 full volume.
It's cheap, something to try.

Class D SDS 470c can find them used for around $400.

Magnepan like many less efficient speaker makers do not emphasize the benefits of more power with their products probably to not limit market or discourage customers.   Less watts will work but you will run out of juice if the volume needs to go up.    Current probably does not hurt but I did find Maggies not as needy there as with many less efficient dynamic designs.  Tube amps even work well if powerful enough to get the volume you want.

My local dealer has sold Maggies for years and recommends Class D amps by Rogue for use with Maggies though they sell tube amps also.  

A lot of good suggestions.

I would second two:

1. Parasound Halo A21 makes Maggie’s sing as good as I’ve heard them (except for the Halo JC1 monoblocks) - about $1500 used.

2. Classdaudio SDS 470C makes them sound as good, maybe better - about $700 new.

I’ve got all of these to drive my Magnestand 1.6’s (Maggie 1.6’s on steroids). They’re all superb.

Tube amps give them great mids, but struggle with bass and dynamics with Maggies (I’ve got some of the best - Atmasphere M60’s with Zeroformers). With Maggies, I prefer good SS amps with a good tube preamp - which gives you a great blend of both.

If your budget won’t allow the tube preamp right now - I’d be looking for a hybrid integrated (e.g. Rogue Pharoah, Peachtree, etc.).