I can add a bit of history. The MP100 was in fact built under the Hafler name for a while. Strangely, a few transitional pieces were built under the Rockford brand. Bill Hannapel designed the signal path, but he told me that he left the control section (digital) to a fellow engineer. I have an ACT version, as well as two of the Hafler models, all with foot controllers. Somewhere in my paper files are the original owner's manual and a schematic.
Although my original ACT unit is the non-tube version, it is still my favorite. An amazingly well thought out piece of gear.
