I have personally owned a few Carver amplifiers but not his latest tube efforts. I am also a current Martin Logan (Montis, which was replaced in the line up by your 11As, so very similar) owner. I think you need to be very careful pairing a tube amplifier with ESL panels. The impedance mismatch is known to roll off the high end. When I first got my MLs, I was using Wyred4sound amplification. I did not particularly care for class D with them. Just my $.02, but I would be inclined to look elsewhere, especially if you do not have the opportunity to try them first. The Martin Logans are possibly a little more picky about amplification than other speakers.
"MartinLogan doesn’t publish impedance, phase-angle or frequency response curves for this speaker. However, they do state that their impedance dips significantly at higher frequencies. This low impedance, (0.6 ohms at 20KHz) with a corresponding increase in phase-angle suggests that amplifiers that aren’t stable into low impedances shouldn’t be used.
MartinLogan’s online FAQs recommend an amplifiers that doubles in wattage between eight and four ohms and again increases its wattage at two ohms. This would seem to eliminate most amplifiers from consideration."
This tells you what sort of amp to look for, and it's not tubes, if you want to extract the very best out of these speakers.
But if your happy with "a bit of a compromise" the the Carver tubes will be fine.
an10490413 OP18 posts03-05-2019 7:09am
Yes they need amps that are stable, but that can also supply current, so look for amps that can "almost" double (or considerably increase) their wattage from 8ohm to 4ohm and again from 4ohm to 2ohm.
You might also want to go to the Martin Logan Owner's website and inquire there.
My choice would be the Carver amps. I'm sure the Theta would work great, but I'm not quite sold on digital amps.
I've heard the Carver's and they are nice.
I have owned Martin Logan speakers and currently own a pair of Monolith IIIs with Krell KBX crossover and Pearless woofers. My Audio Research REF 250 amps work and sound just fine thank you. With my Mark Levinson 23.5 or Modifiied Bedini 250/250 mk II on the woofers, I'm doing just fine.
If you can demo the Carvers in your home with your system and the same with the Theta, that would be the way to go.
If not, find some dealers that sell the amps with those speakers and go listen. If that isn't possible, then go listen with similar setup.