A few years ago Sound Lab showed at CES with Viva amps, and from what I understand they worked quite well together. A number of Sound Lab owners went on to become Viva owners as well. Since Sound Lab electrostats are, if anything, a more difficult load than the Martin Logans, I think you'll be in good shape with the Vivas (within the amplifier's inherent power limitations of course). I've never heard the Vivas on electrostats personally, but I've heard 'em on Kharma Ceramique 1.0's, and so far it's the best-sounding amp I've heard in that particular system.
Best of luck to you,
Duke
Best of luck to you,
Duke