To avoid overload, I've only played this once so far, and will do so a few more times before I post anything lengthy about it. Until then, a few points to ponder:
As noted already, the approach by Mr. Giles--IMO a sensible one--was to reference the mono mix's nuances when remixing for stereo and 5.1. Rather than bitch overmuch about that, most of us will, I believe, applaud it. This means a less 'radical' mix, perhaps, but one with less gimmicky elements and general frippery than we used to hear on the *more adventurous* 70s quad albums. I never minded a bit of gimmick and fripp myself (heh), but do remember that an album like IN THE COURT OF THE CRIMSON KING doesn't have much in the way of sonic gimmicks, either. Yet its sonics are so revelatory that I, for one, was glad there were no significant added distractions, however fun and temporarily impressive such things can be.
This is not to say Martin mixed TO mono, or to the point where the sound is ultra-tight and maddeningly not very discrete (you know where to go for those!) What he has obviously done is use the mono mix--and yes, like mono PET SOUNDS, will always be the definitive refenence point--as a launching pad for how loud and prominent this 'n' that is, or how subdued other elements are, along with tape speed corrections, etc. Beyond this is the fact that the music, in whatever format, was razzle-dazzle regardless and so, rather than pile on too many 3D and other flashy effects that arguably could have added even more dazzle, he opted to let the intricacy and sheer creative force of the group at this time speak for itself.
It's easy to forget that for rock, soul/R&B and some pop of the time, mono was THE reference standard, the *money mix*, if you will. It's where most of the time and money went, not least because a) singles were mono (stereo singles making a slow but steady comeback beginning in early 1968), b) most albums contained the single mixes were applicable and c) our equipment, like our youth, was generally undisciplined and raw, and not always of the greatest quality (but sometimes with total fondness for what we can never have back), and some of our machines were, yes, still mono (though I had a small portable stereo setup with lightweight tone arm by early '67). You don't have to confine yourself to Motown to find the money mono mixes, either: until stereo editions were slowly phased out during '68, a mono Lp was a given for most acts, as was a separate stereo Lp. This 'dual inventory' thing was abandoned by the labels not because mono was inferior (which it never was) but because with stereo-only inventory, the labels were guaranteed more profit per unit, as it were, since mono Lp's were a buck cheaper (which I know explains why Mom always bought us mono Lp's!)
I'm also very weary of giving this one a '10' just because it's PEPPER, if only because--although I've always loved it--have never considered it the 'Greatest Album Ever Made,' as Rolling Stone, among others, would have you believe. It's a singular experience, gave birth to a ton of nonsense via all the inferior rock groups ever spawned (and otherwise would never have been heard, safe to say). But honestly? My go-to Beatles album is either PLEASE PLEASE ME (early) for its vitality, and REVOLVER (midway) for its clever, endearing sophistication and (let's be honest) pretentiousness. I like a lot of the WHITE ALBUM, about half of ABBEY ROAD (overrated, IMO), snatches of LET IT BE, and some beauties from beginning to end (including the US RUBBER SOUL over the UK, though both are great).
Needless to say, I'll be back...
ED