Hi Ian,
Stumbled accross this discussion. Wanted to let you know. I have exactly the same setup as you in one of my music rooms. Grimm Mu1 to Kassandra. And for me the best configuration is 2x on the Grimm plus turning on the Kass clock also.
disabling one or the other somewhat gives the same effect. Presentation is less fluid, less vibrant and abit dry in comparison to having both clocks on.
I would never give up my grimm mu1. Although ive not had a chance to compare to top Aurender n30 in my system ive had a chance a/b with lumin u1, and auerender a200. Although they are not same price range as the Mu1 but the difference wss sooo astonishing that it made the two sound like a fisher price cassete radio lol. Kidding aside grimm sound was analog like and had a huge natural sound reproduction. When goimg back he other two sounded anemic, flat and no meat.
ive heard the n30 in same room with n200 and although n30 was clearly superior to n200 it wasnt as big a gap as the grimm vs n200. Not sure if it means anything as they were tested on different systems. But just reporting the scenario and what i heard.
best
Victor Sierra