All of Outlaw's multichannel amps are manufactured in California by ATI. The designs are specific to Outlaw, although I would expect that a fair number of components are also used in other ATI designs. (There was a review some years ago that found very little difference between the internals of the Model 7900 and a Lexicon 7x300W amp that was also manufactured by ATI, for example - the reviewers didn't have access to a 7900 to make a complete comparison, though, so there was never a formal comparison made.)
This partnership goes back to the original Model 750 in the late 1990's. Outlaw's never made any effort to conceal the fact that
they do not own any manufacturing facilities of their own, and ATI is widely accepted as a very, very good manufacturer of power amps.