What is the best premp for Atma-Sphere MA-1 3.3 amp?

@chungjh to answer your question I don't think room size was a factor. As I mentioned I knew the A-S M60's did not have enough power but I tried many other amps as mentioned earlier as well as Gold Note 1175 and a customer even lugged over his Hegel H30 and still could not get 545's to sing. Again I've loved their bigger offerings which is why I custom ordered the 545's in a Birds Eye Maple frame, the speakers looked fantastic! 
Since I love electrostatic/panel speakers I then went to Sanders 10e speakers which worked GREAT in the same space. 

(Dealer disclaimer) 

@sksos 

Are you using the Sanders amp with your 10e?  How does it compare with the other amps that you tried?

@chungjh  Yes I tried the Sanders Magtech amps then tried the Bricasti M25 amps. Bricasti brought out more 'soul" to the music so used 2 x M25's to drive the 10e speakers. (My opinion is using 2 of the same amps on the speakers is the smart thing to do....Roger Sanders may/will disagree). Yes the magtech has more power but the Bricasti never had a problem with my listening levels at 85-92 dB and peaks in the high 90's.    
(Dealer disclaimer)

@OP
I just did a quick google on the m545's ( I don't know which level you are using- Audiophile/Majestic/Ultimate, not that it seems to make a difference in power requirements). All seem to be 50-500 wpc.
So, the MA-1 should have plenty of power- unless you want rock concert levels.
The Sanders and Bricasti seem to be SS amps. Are you interested in SS?
Bob

I don't listen at rock concert levels. Some people have recommended Pass X350.5 for SL because of its "tubey" sound despite being SS. But as Ralph at A-S stated, at bass frequency, impedance is 30 ohms and X350.5 is only putting out about 90 W. SS is fine with me, but it seems to me MA-1 will give more even SQ across the frequency range. Of course, X350.5 is giving out 350W at 8 ohms in the frequency range where most music lives and is therefore much more powerful than MA-1. Then the question is whether I need 350W in the flat portion of the impedance/frequency curve if I don't listen at rock concert levels and my room is medium size 400 sq ft. What do you all think?