Solid. Thanks! Great links! I appreciate it.
In a couple instances in Recording the Beatles, two of the engineers are quoted as saying that "the lads" (which one(s)? They don't specify) always used to ask them why they couldn't get the "great sound" of the American versions. Malcolm had to patiently explain that the mastering equipment in Hollywood was better than anything EMI would spring for at home. Not surprising, I suppose, since it took them until 1968 to buy an eight-track machine! The louder bass sound in "Paperback Writer" and "Rain" was a result of Paul complaining enough to provoke Geoff Emerick into getting a nice low-end. He wound up recording Paul's bass by, believe it or not, using another huge amp as a microphone.
Anyway, why would the mastering equipment (i.e. cutting lathe and associated EQ boxes) affect the mixes themselves (on tape)? Because while mixing, the engineers had to take care not to make the sound too rich, especially at the low end of the frequency spectrum. The needle would jump right out of the grooves if the song wasn't EQ'd to take the lathe into account.
In An Oral History, the US Capitol guy says the same thing about how the Beatles liked the American sound better, but of course detested the "butchered" albums themselves.
It makes sense, when you think about it; even if one disagrees with the Beatles' taste in sound reproduction itself, they'd been potty over Motown and other American music, which was almost always drenched in reverb up to that point. That's not to mention Elvis records. They probably heard themselves as sounding more genuinely rock'n'roll with the American trappings in the mixes.
I might be weird in the extent to which I prefer the American stuff. I always think rock music sounds best when it seems to have been recorded in a big cave.