Appropriate Power for 1.7i's

The Cronus is underpowered for Maggies unless you have a small room and don't listen to dynamic music at 90dB plus. But it's a good sounding amp otherwise.

Here's the issue: current delivery. Tube amps don't cut it unless they are about 150 watts a side and use 2 pairs or more of paralleled power tubes. Sorry. I made a comment earlier about tube watts not being different from solid state.

Otherwise you're consistently listening to an amp that is distorting. It may generate nice sounding even harmonics whilst doing so...

Mark,
I’ve been a Maggie owner since the early 1980s. Currently, I also use 1.7s in my system. Two pair in a quad setup. I was using a pair of Adcom 5500s. (I don’t know how the one guy found them to be dull. Everybody raved about their open, airy and spacious sound.)
Anyway, I recently decided to switch amplification and ultimately decided on Bryston 4B STs. They provide the same open, airy & spacious upper midrange and highs as the 5500, but with an added depth and articulation to the lower mids and bass. An excellent combination with the 1.7s in my opinion.
My point to you is that $1,600 is way overpriced in my experience. I just paid an average of $1,050 for mine. For that price you should get an amp in excellent condition with some remaining warranty.
If you haven't already done so, set yourself up on HiFishark.com and save a search for whatever amps you have an eye on.  Hifishark tracks listings from, about a half dozen or more web sites (Ebay, audiogon, US Audio, and others).  You can also see sold listings and expired listings which will help you get a better feel for pricing.
Shop around. Enjoy.

Toolbox

50 watts of a quality 2 channel amplifier is plenty of power if your room is not super large. If you desire more power, it will not hurt. I'm using 2 amps now on 2 different setups and the power is sufficient on both systems. Forte 4a on ML Request and Threshold SA/3 on Magg 3.5s. 

I've owned Maggie's for quite some time and had the 1.7's for a while before going to the 3.7i's.  The mags simply ate some amps I tried.....chewed then up and spit them out.  There aren't many integrated or HT amps that are going to get the full potential out if those planars.  Some folks say they are quite happy with the sound with what they have, but until you hear those ribbons sing with a solid power supply you won't know what your missing.  Magnepan used to show their amps with Bryston and now use Pass labs.  Both high current designs that are pretty stable.  I've recently gone to Odyssey monos that are stable below 2 ohms.  They run only around 375 watts at 4 ohms, but put out massive current as there is 200000 microfarad of high quality capacitance and have an 850 va massive toroid.  And that's PER SIDE.  Great damping factor also that has brought the bass out of a speaker they say is weak on lower end.  So now the amps are exerting control on the speakers instead of the other way around.  Absolutely the best sound out of Maggie's I've ever had and the amps don't even break a sweat.  I match these with a tubed pre or tubed DAC and  I'm in audio heaven whenever I sit down for a listening session. Klaus Bunge of Odyssey is pretty well schooled in producing amps for difficult loads as his designs are based on the excellent Symphonic Line amps.  He will custom build a stereo or some monos for not a lot of money.  And you'll die a thousand deaths when you realize what you're 1.7's are capable of.  Current....current..... current.

@OP
A used DNA-1 (unmodded), should be around $800-900. They come up frequently. If I were you, I'd wait. Also, contact SMc Audio in CA. Steve McC is upgrading all his old equipment. I'm having my DNA-1's converted to monoblocks as we speak/write. He might have a DNA to sell, too. 
I'll PM you with some other info.
Bob