I also know Bill, and let me assure anyone who was left wondering by a prior posting that Bill Parish is a man of unquestionable integrity. I had the opportunity to A/B compare (streaming the exact same tracks) the Grimm MU1/Tambaqui vs. the Grimm MU1/Grimm MU2 (albeit, unfortunately, with different — but very good in each instance — amplifiers and speakers) within a couple of hours. To my ears, the Grimms together provided a more convincing performance. The other was great, but MU1/MU2 seemed even greater.
Grimm MU1/Mola Mola Tambaqui combo vs. Grimm MU2
Here is a great video discussing the very popular question of which is better: the Grimm MU1 streamer with the Mola Mola Tambaqui DAC or the Grimm MU2 with built-in DAC?