I purchased the Innersound ESL 300 for my Maggie 1.6's two years ago.  Before that, I was driving them with a Carver Sunfire.

The Innersound amp opened up everything and the grain disappeared.
The amp is a chameleon.  It has no sonic signature that I can hear.  With
quiet, delicate passages, it is detailed and sweet.  The dynamics can knock you out of your seat.  It is rated at 600 watts into 4 ohms.

When it is idling, it uses less than 3 watts.  My electric bill went down $4
to $6 a month when I replaced the Sunfire.  I leave the amp on all the time.

The Innersound ESL300 was designed for the Innersound Isis, though I found it to be the ideal match for the Maggie 1.6s.  I use a tube pre-amp with it and like that combination a great deal. 

Sanders designed the amp to handle the unusual characteristics of
his electrostatic speakers.  It is true that the Maggie's are not
electrostatic, but they are planar albeit not as thin as the planar strips
used by the Innersound Isis.  He maintains that a major source of distortion in the top end of electrostatics (and I include Maggie's) are the huge power supplies in the power amps necessary to drive these speakers.  He compensates by not having a large power supply but having 18 transistors per side.  I am not an engineer, but he has a paper on the subject. Any way, the Innersound is now driving my Isis speakers.  I have a double run to bi-wire the speakers.  I play many different symphonies, as well as jazz and some rock. The amplifier handles everything with no effort.  My system, and therefore the amplifier is extremely transparent, neutral, layered, airy, with excellent imaging, beautiful timbre and great dynamics.

The sound stage goes way back.  The bass is tight and nuanced.  Voices are melodic.  The music sings and yet the drums whack.  The strings are seducing and the horns are arousing.

None of this could happen if the amplifier wasn't up to it.  The high end is
open, airy, no grain and no distortion.  The background is black.  The
voices and the instruments are 3 dimensional.

I bought this amplifier on line from an auction.  I researched it thoroughly, including talking to Greg at Innersound before I purchased it.  I have never regretted it.
I had the Carver Sunfire 300 stereo for 2 years with the Maggie 1.6's.  The Sunfire had power and was a nice amp.  I still use it with my movie system.
BUT, the Innersound is better in all ways.  It is in a different league.

I have also owned, and was very happy with the Nelson Pass Aleph 3 and the Conrad-Johnson MV 52.  I used both these amps with my Fried G-3 transmission line full-range speakers.  These were my main speakers for 10 years.  The Fried's are a more efficient speaker so they don't require as much power. However, the bass goes down to 20hz.  So, weak basses need not apply.

I had the MV 52 in my system for 10 years.  It is a sweet and detailed tube amp. The Innersound is more neutral, more dynamic, tighter bass, and more transparent.  I really liked the MV52 though I like the Innersound better.

The Aleph 3 is a jewel that I had with the G-3s for the last 15 months
before I changed to the Maggie 1.6's.  The Aleph was sweet, airy, detailed and musical.  For a small amp, it was very dynamic.

However, my system is much better now with the Innersound and Isis.  It was also much better with the Maggie 1.6s and the Innersound.

John B.