@audphile1,
I also installed the Bricasti MDx upgrade board in my Bricasti M21. My system sounds clearer, smoother, more engaging with more musical details. I like it very much and also highly recommend the MDx board upgrade.
Please read the instructions carefully since it requires you disconnect some cables, remove the old board and install the new board. I had someone help me and the job took about 45 minutes (we moved very slowly).