I just swapped my MR78 out of my main system and put the MR80 in, well, yeah I have to say the sound reproduction from the MR80 is excellent, its tighter, and has more clarity and well as a more open top end....best sounding tuner I have ever heard...
I'm going to look at the de-emphasis on the MR78, we in New Zealand here are 50µS, and I feel McIntosh haven't got it quite right, there probably aren't that many 50µS MR78's out there and was a small market, so might not have looked into it as much as the USA 75µS standard......
I was a Japanese Receiver junkie, and to be fair, some of the high end Pioneer and Sansui tuners i had, were/are very very good and cannot be underestimated!!