I haven’t heard the Pass combo, but I have heard the North 761/791 vs the 861/891 at some length. The 800 series is more resolving, smoother (more liquid) and more musical though both series are very, very good and a signficant step up from Sim’s previous offerings IMO. I also agree with @audiopacer in that there are many factors influencing the result but the electronics are unlikely to be a limiting factor.
I ended up purchasing the 761 amp for my 2nd system as it was close enough for me and would fit in my cabinet! There is a greater difference in the 891 vs the 791 preamp/DACs.
If I hadn’t already been well down another path with my better system, I would likely own the 861/891 pair. Elegant and simple with remarkable sonics.
Best,

