If Led Zeppelin sounds good on an audiophile system, then it's not an audiophile system in the common definition of an audiophile system.
Might just be my disc set (remastered collection), but Staiway to Heaven on my system will match virtually ANY Audiophile level recording.
From the opening acoustic guitar, it is enthralling to say the least.
However, I agree that MANY 70's recordings may not sound that good (for that matter even recent recordings)