Lowrider- Siddh, in a posting above quotes from a Rolling Stone article that describes these as mastered from hi-rez digital and I have seen other articles that say the same. For what it's worth, though I am pretty much a dyed in the wool analog guy, I have heard digital mastered vinyl that has actually bettered original analog pressings; one example that comes to mind is the Steve Wilson remix of Tull's Benefit- I have a first UK press, a first US press and both are murky, closed-in sounding. The Wilson version is far more revealing without sounding strident.
As to other Zep remasters done all analog, I'm sure the Classics were, as Rockitman indicated; there were also many older reissues and remasters, including, for LZ1 the Piros one I mentioned (which is really good, circa 1974); the old MoFi of LZII (which isn't bad). If you go to Discogs, you can see dozens of reissues by country that were done back in the day before digital become prevalent.
We did a shoot-out of LZI at my house last year which included a UK first pressing (not the turquoise lettered cover, but same matrix numbers), the first US (I think a Presswell) and a first US pressed at Monarch. The last one had far and away more drive than the other two. (At the time, I only had the 33 Classic of LZ1 so we did not compare it to the 45 Classic, which I only acquired later).
I haven't heard the 45 Classic of LZII but FWIW, the 'RL' is far 'hotter' than the other early US pressings of that record.
I'm offering this, not because I purport to know everything Zep, but because I have spend some time and money comparing and buying pressings of these. (And yes, the 45 of Stairway is very good- you can find it out there- I bought a test pressing last year).
Don't ask me about Aqualung, another one of those records that just isn't a great recording to start with, thus driving me to buy an almost endless number of different pressings in search for the best sound.
