Magnepan 3.7i Amplifiers Aesthetix or Modwright? Thoughts?

Have a McIntosh MC-602 amplifier running them now, looking to up the game.  I currently have an Aesthetix Rhea Signature and Calypso Signature, so naturally looking at the Atlas Signature.  The Modwright KW-150SE running as a monoblock via a bridged config though sounds compelling.  Obviously, I would need to demo these.  Question:  Who's got experience with either of these running tough 4ohm loads?  Maggies want serious current, and both of these probably would fit the bill.  My guess the Modwrights may be a bit more airy, which is great, but looking for better control of the bass from 100 down.  Any experience or thoughts shared would be most appreciated!   Thanks!
What do you NOT like about the Mac?  It certainly has enough power and current.  Current is over 60 amps per channel and probably closer to 90 amps.
Looking for a better top end and midrange.  That 602 has an iron like grip on the lower registers, the McIntosh 'house sound' needs to get changed up.  While the mac has served me well for many years, it's time to move up the food chain.  I have a secondary system i can move that into and enjoy it there or may just put it up for sale here, not sure the existing cabinetry can handle a 180lb amp!
I wish I had the room for it.
Up the game from a Mac 602? Differences yes, up the game... not so sure, at this level things are different not better going from 602 to a Modwright 150se??? moving backwards imo. I would look at the pre amp to tune your systems sound as well as cables...Keep the MAC!

I have an Aesthetix Atlas and Calypso. They are a great match together and my system has never sounded better with the addition of the Atlas. 

Great grip and control on the bottom with a sweet, but detailed and articulate top.
What did you have before amplification-wise and are you currently running the 3.7i?  

I was using Quicksilver V4 amps. I currently use Proac speakers. You can see my system which is posted on Audiogon.
The higher impedance in the Atlas
monos with your Caylipso will seem more alive then either. Add to that you can also activate the variable built in high pass within the Aesthetix will help you adjust
the bass till it's just right for that room great amps
You may want to consider Bryston,that is the amp Magnepan reps use to demo their speakers.
I have not heard those particular Mac models but the Bryston 7B series monoblocks would be good options. I wouldn't consider them an upgrade per se but more of a lateral move with a different sound signature, e.g., tighter bass, more balanced and not quite as warm. I personally prefer the Mac house sound. You should definitely try it in your system before making the switch.
Still possible to biamp the 3.7i?  I'd recommend Pass Class A on the top end, and then a quality Class D for the bottom.  Sweetness for the highs and middle, tightness and power for the bottom.  But I guess that would take an active crossover, which would be a pain.
3.7i cannot be biamped.
I agree that Mac gear can be bettered.
I use my old 4B-SST² with my new Magnepan 20.7s.
(Just got them.)
When I can again afford a big spend I may get the Bryston 7B3 as, Bryston is the #1 recommended amp to pair with Magnepan.
Sorry I have no experience with the amps the op is interested in.
I mainly posted to brag about my speakers, and mention the 3.7i cannot be biamped (nor can the 20.7)
The current .7 Maggies have series cross-overs, consequently they can NOT be bi-amped (without serious surgery). The .6 and earlier models have parallel cross-overs, so can be. It is for that reason Maggie aficionados who prioritize bi-amping prefer the .6 models.
I’ve been powering my older 3.6 Maggies for 10 years with a pair of Bryston 7BSTs (a long time for me to stay with the same components). Aside from the well known, slightly weak low bass (compensated for in my system with an REL Stentor sub), the Brystons allow the Maggies to be everything they’re meant to be, with ease—a textbook example of clarity, immediacy, spacial definition, detail, end every other quality the speakers are designed for, with power to spare. My equipment predates yours by many years, but I’ve never had (nor heard) an amp/speaker combo that sounded better, certainly nothing near their price point. Some day, when I update to the 3.7 (or, in my dreams, the 20.7), I’ll stick with my trusty Brystons (though perhaps in a more modern incarnation if I win the lottery).