Led Zeppelin’s classic albums never sounded this good. The latest reissues feature the original albums remastered by Jimmy Page and accompanied by a second disc, presenting an alternative version of those same LPs, usually through alternate mixes. The previously unreleased take of “The Battle of Evermore” is a lovely instrumental with mandolin as the dominant instrument. Page doesn’t clean up the original sound but brings clarity and resonance without loss of power. The early mixes reveal nothing new about the songs but are revelatory about the choices made in rock productions in the early ’70s, with every channel of instrumentation acting as a distinct sonic color on the artists’ palette.