Experience with Simaudio Moon North amps

Thanks for asking the question Craig, I’m interested in that too. You have a very impressive system. I Auditioned the 761 in my system, Looking to improve on my Michii S5. I could not hear an improvement, certainly not one I would write the check for. I like simaudio equipment And was hoping this would be a keeper, but for me, it was not even though I’m sure it’s a fine amp. I keep trying to improve on what I have, but I think the Michi  maybe punches above its weight. I’d certainly be interested in the 861, however, if it is the kind of improvement described and would be very interested in the answer to your question from someone with experience.

Interesting experiences above by other members. Synergy is key, as always. When I first received my 761 it was paired with Opera Loudspeakers, Diva Callas (latest version). The Divas are interesting speakers. Very capable, excellent separation of fine detail, very resolving. Over time with the 761 I played around with different cables and found the 761 to be very revealing of upstream gear and pretty much all ancillary equipment. It is NOT a forgiving, rounded golden amp. It is pretty much dead neutral, presents a super low noise floor, is very fast; hard to summarize in  a few words but it is an extremely highly capable amp. I am still learning more and more about music and tuning the system. 

Fast forward: a few weeks ago I auditioned ATC SC40 passives with the  641/681 and was so impressed and blown away by the organic synergy and overall performance I purchased the SCM40s. It's been a pretty short time since I have been listening to the 761/ATC pairing but I know synergy when I experience it. This is synergy like Luxman/ Harbeth, or Pass/Wilson. If you need more power for sure go with the larger amp, but do not expect the native character or "house sound" of the North series to be greatly different. I heard this with the 641 in my own house on the same opera speakers. The 761 had more control and more overall reach in to the stage and all that, but the colors and dynamics of the source were able to shine through in all the glory in either case. 
@kerrybh please update the thread if you get to hear the larger amp in your system!  Happy trails!

I will and I hope to hear the 861. I had a simaudio 390 in my system for a long time and currently use a simaudio phono stage. Simaudio builds good, high quality stuff. I’m a fan 

I have the SIM audio 861 and comparing it to the 761 everything is just that much better the separation, air and space between the instruments decay of the echo, the voice sounds more human and I think my estimation was wrong now that I've had it for a while I think it's even more than 25% better than the 761, because of the MDCA circuitry this is the only amp that I know of that has no local or global feedback and I believe that this amp will beat amps in the 40 to $60,000 range from any other company It's that good. Lookout Boulder and Gryphon.

Zuesman that is great! Happy you love the 861 so much. I’m also smiling b/c that implies, by your calculations, the 761 beats amps in the 0.75 x 60,000 = 45,000 range ( it’s about 75% as good as the 861). I have never heard a 45k amp, much less had the opportunity to directly compare such amps in my specific system, so I can’t comment, but I can say the 761 is phenomenal across the board and has beautiful synergy with ATC. I also found that the 761 responds well with a DPS 4.1 power cable. Happy tunes!