Just one point of contention, Bonham's drums are so compressed on every recording I have ever heard or owned and that is a real shame. Rock recordings in general at the pinnacle of the genre are plagued by bad recording/mastering of drums and cymbals, Zeppelin is far from alone. Don't get me wrong, I grew up with this music and have a great passion for it, Zep is huge in the Rock pantheon for me and many, needless to say but Kublakhan why spend a small fortune on something that will never sound excellent. Grab the 33 1/3 pressings if you need them and spend the rest on other vinyl. I truly believe you will be reasonably happy this way. I wish Classic no harm, its just a bad investment IMHO.
Just a comment on the digital recordings in the Led Zep Complete Studio Recordings Box Set [ORIGINAL RECORDING REMASTERED] that was originally issued in 1993, for CD they are very nice. The sound quality is very resolved with great detail. You can even hear Bonzo's bass drum pedal (I say) or possibly (some say) his seat squeaking on Willie Dixons I Cant Quit You Babe, or was it You Shook Me? from the first album. Anyway, not bad!
Happy Listening!