Recommendation for a highly resolving amp

Another vote for the Benchmark AHB2.  They have a free 30-day trial.  BUT, it only accepts XLR/balanced inputs.  Not sure if your Don Sachs has that modification for outputs, or else you'd need adapters.

@edilita, Unfortunately friend's Spectral amp only works with a Spectral preamp.

@jdjohn, Don Sachs does not have XLR, I could get the RCA-XLR cable from Benchmark. How do you like AHB2?

@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.

https://audiophilestyle.com/ca/reviews/power-amp-comparison-cambridge-edge-w-benchmark-ahb2-bryston-...

A detailed comparison with the 4B3 & AHB2.  The AHB2 is without a doubt a nice piece, and at it's price point, perhaps the best option.