Charles1Dad-
I liked the SIT-2 very much, although wondered if it was a bit dynamically limited- above 92dbs or so I could hear it distorting in my room. It doesn't have tube decay, so is still a different sound than tube- but it has a very similar midrange to great SETs. I was really astonished by it's sound at times.
I ran it with a McIntosh C2300 tube preamp w/ NOS teles, so clearly not a DHT preamp. I really don't have interest in the monos as they don't increase power. Doesn't seem like anywhere worth 2x the $, bias adjustment or not. The gem of the line is the stereo version imo.