IME, the Luxman Class A/B amps are a lot more linear than the Class A amps, which tend to be rather smooth, which is exactly NOT the thing to do to a Merlin and adding Cardas cables into that mix is a hot mess.
I like the Mac integrateds quite a bit. Well, I'm totally fascinated by the chunky dials/buttons and the big blue meters, which I just love, but then, the Luxman has them too, so there you go. Totally my opinion here, of course, but I think that the Luxman has a much higher build quality and wrt the sound, I think Lux has a (significantly) more extended and linear presentation, both in bass and in the treble. Both Mac and Lux have a very fine mid range presentation, however.