Can't speak to the newer gear by Dan, but I did have a Krell KSA 50 MK I that was very reliable. Also great sounding. As for why Dan started D'agostino Audio, I remember reading an article about Dan and his then wife, Rhondi partnering with some other people from Madrigal. They became annoyed that their chief engineer was fired by some of the new partners and voiced their disapproval. As a result, when Dan and Rhondi came to work the next day, they found the locks to their office changed.
So began the legal battle between the D'agostinos and the Madrigal people.
Ultimately, Dan decided to start D'agostino Audio. His gear is really audio jewellery for the well heeled and from what I have read quite good sounding.