I would personally steer away from tube amplifiers with ML. While I'm sure those Manley monos are very nice, they explicitly state the optimum speaker impedance is 5 ohm and the output impedance is 0.538 ohm. The ML panels are very capacitive and the minimum impedance is 0.6 ohm at 20 kHz, so probably not a good match. If you crave the tube sound I would look at a hybrid design, since you already have your source/pre. For what its worth I have the predecessor to your ESL11A (Montis). I power them with Pass INT-150. I think Pass amplification works well with ML. I'm sure there are many other (less expensive) alternatives that would work as well.
