they are both very very good, excellent performance in absolute terms and terrific values for the cost -- each is built very very well, especially the kinki, which is designed in a brilliant modular fashion
they both have prodigious power (you did not say your room dimensions and speaker of choice) to drive most if not all speakers to good levels in reasonable sized rooms
to my ear, the kinki has a purer treble than the mf but a slightly more recessed midrange, both have outstanding bass, mf has a tiny bit to lower treble forwardness and a slight fine grain (to me sonically the mf units to buy are the older ones, say a308 series, or the ones with a mu vista front end, what lovely sound)
you are right, kinki lets you roll op amps, in my ex m1 using sparkos made the sound even purer, cleaner and a touch richer
the kinki is from a chinese company, made in china, with a service center in texas
mf gear is assembled in taiwan, not sure where their usa service center is, i am sure their current importer has one or more usa service partners do any warranty or repair works as needed
