This looks like as good a place as any to post this.
A while back I was thinking about what part of the board on the pmd661 gets the coax in jack, and what it would take to modify a pmd620 to have that digital in. I've opened both up and had a look inside, but it's not a job I could do. The 661 has a lot more connections and the 620 has 2: mic, which accepts phantom power and line, which doesn't.
Does anyone know what would be necessary to modify the 620 to collect its info from a coax digital in?
It wouldn't have to do anything but pull in a signal at 24/48 or less, since that's all the unit can do, but it's a tiny, lightweight simple piece of equipment and the simplest one I could think of.