"III" (Vinyl + CD)
Today I'm listening to this 1970 release on an original vinyl pressing on my secondary hi-fi which is comprised of all-vintage pieces. (Marantz 1152DC, AR-X1 and Dynaco A25's for those interested.) I find this beneficial to do with some of these older rock n' roll albums that definitely benefited from a later re-mastering. I would say AC/DC and Led Zeppelin's records both got a much-needed facelift when updated for listening in a digital age.
That being said, it's an education to listen to this music, conceived and written during the Age of Analog, through similarly aged stereo equipment. I know all of these songs well (I don't think we need to discuss the merits of Led Zeppelin III, do we?) and hearing them as they were enjoyed initially is a lot of fun. A lot of the edges (sonically speaking) are rounded off and the stereo itself blends the recording together a lot more than modern-day stereos would. I encourage the exercise if you're able to do so.