Recommendation for used Amp to power Magnepan 1.6

Yes - the Parasound Halo A21 is great with Maggies - I use one, as well as the Parasound Halo JC-1 monoblocks.  

Or... if... you want to try a class d amp - the Class D Audio SDS-470C sounds great with Maggies - which I also use with them.

http://classdaudio.com/sds-470c-class-d-audio-power-amplifier.html

There are a few Rotel rb-1080’s on eBay now. One of them is near $600.
They are 200 wpc @ 8 ohms. They’ll be in the 300 wpc range with your 6 ohm Maggies.
I have a Rotel rb-1070 driving mmgi’s and at 130 wpc @ 8ohms...it does a great job driving the 6 ohm Maggies.
The Rotel rb-1070 drives them better than my 100 wpc Parasound htc-800 ii and my 100 wpc Rotel rx-1052 ever did.
The rb-1080 was Rotel’s top of the line amp.

I'm using a vintage Classe Audio DR-9, the last product engineered by David Reich, the uber engineer of the Classe heyday.  It's very high current into 4 ohms and performs well with the LRS. I have no idea what it costs on the used market though.
Keith

I was using my Aragon 8008BB to drive my Maggy 1.7i with excellent results. It's a dual mono amp that is very high current. 200 watts at 8 Ohms & 400 watts at 4 Ohms which the Maggie's is rated at. I got the upgrade bug & bought a PS Audio BHK 250. While it's amazing with the Maggie's the Aragon holds it's own. I'm selling mine for $900 + actual shipping costs. The Aragons are built to military spec & last forever. A truly iconic amp at that price point & have stellar reviews. 

Re: Rotel-  Rotel amps seem to be one of those amps that people either love or can’t stand.  I personally never though they were that great,but love my Sunfire and there are plenty of people that hate Sunfire.  

Re: Aragon - Great amps that double as room heaters.  I would suspect most need the caps replaced by now, but if the cost of doing so is reasonable, the 4004 and 8008 are great with Maggies.