Mono vs stereo

Isn't that how Harry does it?

Not sure, but that is how my neighbor has his set up.

bdp, yes, the later Beatles mixes can be very different between stereo and mono.  Listen to the stereo version of the song Yellow Submarine and you don't hear "a life of ease--everyone of of us" and on the stereo Sgt. Pepper's Reprise you don't hear McCartney's "barker" shouting at the end, right before the segue to A Day In the Life.  Somebody fell asleep at the board on those.  But the early Beatles recordings are not that way.   As I said, the mono mixes of those were (according to George Martin) made from the stereo mix.  He made the stereo mix the way he did to facilitate the making of the mono mix.
 The Beach Boys mixes were a bit weird anyway, in concept, because you've got an artist with only one good ear trying to mix in stereo.  Doesn't work so well.  Brian did assist with the 90's Pet Sounds stereo remix (which I prefer to any other mix of that work).

Regarding Beatles albums, the group was largely involved with Martin for the mono mixes but spent very little time, in some cases none, for the stereo mixes. They felt the true expression of the recordings were the mono versions. 

Right tostado, Brian Wilson being almost deaf in one ear is why he always mixed to Mono. And though Capitol Records insisted on putting Nik Venet’s name as producer on The Beach Boys albums, Brian was producing them right from the beginning. What would Venet know about putting Four Freshman-style vocal harmonies on top of Chuck Berry Rock ’n’ Roll and Dick Dale Surf songs, which is what the early BB sound was? And though the recording studios Brian used had Union rules requiring one of their engineers be at every session, Brian did his own mixing. No other Artist in R & R had ever done that, though Buddy Holly came close, working with Norman Petty in Petty’s small independent Clovis New Mexico studio.