Recommendation for a highly resolving amp


I have Don Sachs 2 tube preamp driving Pass Labs X350.5 driving Sound Lab M545 ESL speakers. I like the sound very much, but when I went to hear my friend’s Spectral system (driving Quad2912 ESL) I realized my system can benefit from having a higher resolution amp. Spectral amps need all Spectral preamp/cabling, which would be quite expensive. What would you recommend?
128x128chungjh
@chungjh, I enjoy the AHB2 quite a lot.  It is very transparent and clear, with no coloration, especially when compared to typical/traditional class A, A/B amps.  It has a small footprint, and barely runs warm.

I had been running a PS Audio S300 class D, which is also quite clear, but the Benchmark AHB2 sounds better to me (and many other owners).  Again, it is very transparent, with no harmonic distortions to add warmth or color.  I'm not saying those things are bad...it is just different, and comes down to personal taste.

I also have two different McCormack DNA amps, and a Symphonic Line amp (which was the inspiration for Odyssey amps).  These are very fine amps that have a nice warmth to them and plenty of power (can run a little warm if driven hard).  Of course they are big and rather heavy as well.  But, as far as 'highly resolving', the AHB2 brings out more detail.

I have actually gone all-in with Benchmark at this point.  I have their DAC3/HGC preamp, HPA4 preamp, and the AHB2.  I should be set for awhile :)

FYI:  I had a Don Sachs Model 2 for a bit, but decided that tubes are not for me.  I know Don made some units with XLR outputs, but I think he quit that, and I know he no longer does mods on older units, except (I think) for original owners.
I have an all Benchmark stack in my living room (with KEF LS50) and that is my favorite gear, DAC3B | LA4 | AHB2 x 2. I even owned the HPA4 before I sold it for a profit. So some poplar gear. However, I do not think the AHB2 would work as well with the OP's speakers. 

I have Thiel CS3,7s and while the Benchmark stack sounded very impressive with them there was some missing low end. The AHB2 stereo and mono do not play nice with 2 Ohm dips. It was easy to see this when I replaced the AHB2 with the KRELL K-300i, LSA Voyager 350 GAN, and the amp I settled on, the CODA #8. They all had better bass than the AHB2 on the Thiel CS3.7. On an easier to drive speaker the AHB2 would be what I would use in a heartbeat.
Definitely a good point about the OP's ESL speakers.  Specs for the Sound Lab M545 ESL speakers show 8 ohms (nominal) and 89dB, so *should* be okay???

I have found the Benchmark folks to be very responsive, so probably worth sending them a note to ask the question.

Full disclosure:  I do use an SVS SB-2000 powered sub alongside my JM Lab/Focal Mezzo Utopias.  Some of the music my wife likes benefits from the sub for ultrasonic playback ;)
The best recommendation I can think of is to stay the heck away from
your buddies home. Spectral gear with Quad 2912s? I can imagine nothing better. Sell your stuff and rent out a bedroom in his home. Maybe he needs a chauffeur?
What is his sub array?

Was it determined if the room and speakers are adjusted optimally
as suggested by Atma? Gotta start there.