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

Thank you viper 6.  I have Martin Logan CLX's and have heard mixed reviews of the AHB2 with full range stats.  Most comments seem to find that bridged mono'ed amps work better than a single amp into full range stats.  Benchmark maintains that bridged mono'ed amps are stable into low impedances.  I appreciate your comments regarding the Merrill 114's.  I am curious as which electrostatic speakers you are using.

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

I am sure that you will really enjoy the No. 16.  The differences between  the most 15.5's and the new 16 are the inclusion of newer low noise input transistors and an increase in the capacitance in the power supply from 200,000 microfarads in the 15.5 to 280,000 in the 16. I am fortunate to have a 15.5 which has the same lower noise input transistors used in the 16 but I am sure that the augmentation of the power supply will translate to improved performance.  Congratulations.

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 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 have not tried the Benchmark XLR interconnects as I received advice from other users that they were decent but were bettered by a number of high quality interconnects. Benchmark amps and preamps do benefit from audiophile grade cables - including power cords, interconnects and speaker cables - although their literature does not acknowledge this observation.

I can see from the comments that there are many opinions most of which are well grounded. I regularly attend live concerts - principally symphonic and opera.  I was fortunate to attend two performances of the Metropolitan Opera in February before the pandemic hit New York.  When listening to recorded music I value natural timbres, the minimization of distortion, and the ability to follow the musical intent of the performers.   I agree that the AHB2 has a low noise floor and so reveals details that help to convey the intent of musical performers; in my system I was disappointed that a single amp did not provide accurate timbres from recordings of artists  that I have heard live. No system that I can afford will provide a perfect replication of all live music.  However, one wants to optimize their system within the limits of their resources. Experienced listeners reviewers, not a single individual, have had good results with AHB2's driving electrostatics, including a single AHB2 driving Quads and, contrary to my naive expectations, good results from mono'ed AHB2's with other electrostatics including the CLX and hybrid ML's.  When I started this thread some months ago, I did not have any first hand experience with the AHB2.  I probably need to audition the mono'ed AHB2's, the newer Merrill amps and probably the Constellation Taurus as well.