Will a pair of Manley tube amps be a good match for Martin Logan ESL 11A's?

bdp24 and georgehifi are absolutely correct. You may want to read Roger Sanders white papers to get a contrasting view. I personally am not a big fan of using tube amps on ESLs which like jafox I have been running for decades. One transformer is bad enough. Two transformers is really uncomfortable for my brain. Now OTLs get rid of the second transformer and Atma-Sphere amps have a storied history with SoundLabs but I have not heard this combo yet so I can not speak from personal experience. But I have had numerous amps in my system and as a rule Class A SS amps fair the best the two outliers being The JC-1 and strapped AHB2s. I also cross to subwoofers at 125 Hz so the ultimate low bass performance is not an issue for me. You also cross to woofers I think it is somewhere around 250 Hz but don't quote me on that. Biamping would be a consideration but that still does not negate the issue with low impedance at high frequencies. Trick: put a 1 ohm 200 watt resister in series on the + side of the speaker. This will not decrease the efficiency of the speaker all that much and frequently makes the amp more comfortable with the high end. Digikey has them. These are not little devices. They are mounted in 3 inch X 2 inch heat sinks. I always do this if I have trouble with amps overheating and it solves the problem 100% of the time.

The answer could very well depend on which Manley amp is being considered. For example the Manley Neo-Classic 250 has a specified output impedance in the vicinity of 0.5 ohms (John Atkinson’s measurements reported in Stereophile were 0.6 and 0.7 ohms for triode and tetrode mode, respectively). Those are extremely low numbers for a tube amp and suggest that the effects on tonal balance resulting from the interaction of that output impedance and the speaker’s impedance vs. frequency characteristics will be relatively solid state-like. (The RM-200 mentioned by George and bdp24, by the way, has a comparably low output impedance on its lower impedance output taps). On the other hand the Snapper has a specified output impedance of 1.5 ohms, which everything else being equal will result in a less extended upper treble, compared to the Neo-Classic 250.

I have no idea which of those presentations is likely to be preferable with this particular speaker, or how desirable either presentation might be, or how problematical the deviation from the recommended 5 ohm load might be for the amplifier, but as Jafox suggested it would be a good idea to contact the manufacturers and solicit their thoughts about the specific pairing. If you already haven’t, I would also try to find user comments about amplification others have used with the ESL 11A or with its larger brethren in that series (the 13A and 15A). I would not extrapolate much if anything from generalities about ESLs, or from experiences involving other makes of ESLs, as in most cases the Martin Logans are different animals than other ESLs in terms of impedance characteristics, inclusion of powered woofers, and other respects.

Good luck. Regards,
-- Al

this is the full spec sheet for the Manley Neo-Classic 500 mono blocks. some of which I do not understand.

• LL-TUBE monoblock design 10 x KT90EH Electro-Harmonix Russian output tubes
• High current double 12BH7EH driver stage
• Tungsol 12AT7 large plate input tube
• BALANCED & UNBALANCED inputs
• MUTE switch
• TRIODE / Ultra-Linear switching
• SOFT-START/ EVER-WARM standby mode
• MANLEY Precision output transformer
• Factory set for 5 Ohms nominal
• Front panel bias measurement and adjust (hiding under the black insert)
• Large filter / reservoir capacitors 3800uF x 2
• Angled rear of chassis provides for easy connections
• WBT binding posts
• Input sensitivity: 1V
• Gain: 32dB tetrode; 30dB in triode
• Input Impedance RCA: 116 kOhm @ 1KHz
• Input Impedance XLR: 270 kOhm @ 1KHz; 20 kOhms @ 20KHz; 38 kOhm @ 20Hz

• Noise Floor: Tetrode: -67dB; Triode -65dB typical
• S/N Ratio: -80 dB
• Dynamic Range: 96dB
• FLAT frequency response: 10 Hz - 30 KHz continuous
• Power Consumption: 30 Watts in "EVER-WARM"
• Full power (tetrode): 500W
• Full power (triode): 275W
• Factory set for 100V, 120V or 220-240VAC operation for original destination country's mains voltage.
• Operating Mains Voltage changeable with power transformer re-wiring and fuse value change.
• Mains Voltage Frequency:
• Dims: W=19", D=13", H=9"
• Shipping weight: 82 lbs. each

I was about to provide the same counsel as mijostyn above, and am gratified to read it here before I posted it. Roger Sanders excellent white paper on tubes vs transisters explains a lot.
My .02 is that you probably can pair Manleys with the Martin Logans, but at what cost? Which model in the range? I think you might find the Magtech equal or superior, at a very reasonable cost.