“Separates,” I should say, rather.
Bah…humbug.
After experience, an EQ job sure as hell won’t cut it, unless you’ve got a helluva lot of time and don’t mind doing the frequency analysis by the singular-hertz level. (Voice editing, Logic Pro, Soundtrack Pro and ProTools.)
Cutting the middle phase from a record might work. It depends on how the vocal track is panned in the master. It could work - if you’re lucky - on the end product, but it wouldn’t be pretty.
The best result you could get would be to have a instrumental master. (I.e. where the instruments for studio recordings are synched and adjusted, which is usually done before vocal synch. At least in my experience, but I only work small-scale.) One of these might be up for grabs on eBay for, oh, a couple hundred $100.000.
Actually, now that I think about it, I wonder if they didn’t let slip the mixing master when they digitalized one of the records. I think that was Springsteen, not Led Zep, but it might be worth a cursory google search.
ETA: When I say mixing master, I am transliterating from the Norwegian terminology. I am of course thinking of the session files, not the copy master.
Needed another ETA to my previous post, but missed the window.
ETA2: I don’t think you’ll find them openly available on, er, less-than-legal sites though. I’ve heard rumours that the head of the RIAA keeps MultiTrack Masters under his pillow at night. I’d hazard a guess that a LZ MTM posted on a popular torrent haven would raise a red flag within hours, if not minutes.
ETA3: Oh, and the leaked LZ MTM was the Southampton 1/22/73 live MTM. No words on others, but a few, quite sexy Thrice MTMs I’ve got to track down when I’ve got a moment.