Benchmark ABH2 compared to Merrill Element Series and other ultra high end amps

I am sure that the Audiostatics are great speakers and like most full range or nearly full range electrostatics they present the driving amp with a capacitive load with high to very high impedances in the bass and low to very low impedance in the mid to high treble region.  The obvious exception are the Quad 2800 and 2900 series.  John Atkinson measured a minimum impedance of 3.3 ohms at 10 kHz and then rising with an inductive load for the 2912's.  The only impedance curve that I have seen for the CLX's was published by hifi world; the impedance for the midrange/treble panel on the Montis published by Stereophile is probably representative of what a more detailed curve would look like to the CLX midrange/treble panel.  The impedance in the bass is capacitive and over 30 ohms for the CLX at 50 Hz at the lower end of its range and falls to 4 to 6 ohms in the upper midrange and lower treble.  It falls to 3 ohms at 6-7 kHz and then down to 0.7 ohms at 18-20 kHz all capacitive.
I suspect that the impedance in the bass is unusual due to compound bass driver in the CLX.  Also the sensitivity of the CLX as estimated by British hifi mags was closer to 85 dB than the 90 dB published by Martin Logan.  This long discussion likely has much to do with the difficulty many amps have in optimally driving the CLX.

Since starting this thread, I tried out a single Benchmark amp.  It was as advertised extremely transparent and able to resolve small details.  However, it lack lower midrange to bass dynamics compared to many other amps I have had, Pass Labs 100.5's, Krell 402e, and Coda No. 40 and 15.5.  It also seemed to have a lack of tonal color and density.  I have spoken to knowledgable personnel at Martin Logan.  They have used the Benchmark in mono'ed mode with their hybrid speakers which do have a low treble impedance without any problem; however, they did not comment on the compatibility with the CLX.  Other reviewers, particularly Doug Schroeder, found the mono'ed amps to be noticeably better than a single amp.  Other CLX owners have noted sonic improvement with mono'ed amps.  Benchmark has told me that mono'ed AHB2's can handle the low treble impedance of Martin Logan speakers.  A priori, I would not have guessed such a synergy but I have no reason to doubt the observations of several experienced reviewers and audiophiles.  

I remain curious to try two mono'ed AHB2's with the CLX's but am also curious as to whether I would be better served by one of the newer Merrill amps.  

I did own an AHB2 and yes, it’s very quiet, distortion free. I was happy and then a friend brought over his 30 year old Mirror Image Audio amp a to try out. This amp made the AHB2 sound thin and lifeless in comparison. I now have a Coda #8 and It is even better. The AHB2 just doesn’t have enough meat on the bones for me.

I am now using a recently manufactured Coda 15.5 which has the newer low noise input devices.  My perception of a single AHB2 on the CLX are as above  and consistent with lancelock's observations.   The Coda 15.5 is an excellent class A amp and is able to drive the CLX's well with tonal density, dynamics, bass response and excellent detail provided the upstream components including cables can provide such.  My overall impression is that the Coda is more satisfying than a single AHB2, but that the AHB2 may have a small edge in very low level detail retrieval.  In audio, we would like to have it all.

I should add that this small edge was only seen when using an LA4 preamp with the AHB2 input in the lowest gain setting.

@soundhound

I failed to mention that I’ve had the Coda #8 for about 2 weeks and I’m sending it back.  I will be exchanging it for it’s big brother the Coda #16.  I loved the #8 so much that I’m now going straight to the flagship amp as my end game.