Hi Peter. I'm referring to the Crosby Stills and Nash album that begins with "Suite Judy Blue Eyes"(that is, the album with the three of them on the cover sitting on an old sofa outside a house). The Hoffman version has the better highs. It can be found at
www.audiofidelity.net and also likely on Amazon.
Yes, Barry did do the original CD masters for most if not all the LZ albums. A listing of his masters can be found here:
https://www.discogs.com/artist/389175-Barry-Diament?sort=year%2Casc&limit=250&page=1.
And, yes, he did master Houses of the Holy for CD. It is what it is but at least Barry did not use compression in any of his masters. I don't have a Diament master of HOTH so I can't otherwise compare with anyone else's.
You would need to check the back covers to determine who did the CD masters for each disc. As you know, different versions have appeared over the years, usually with the release of boxed sets.
Diament masters turn up here and there on ebay. I have the first LZ album and Physical Graffiti in Diament masterings(the latter having been picked up on ebay).
Jimmy Page takes producer credit for all versions of all LZ recordings. The 24/96 hi res remasters were credited to Page though I'm not sure who the engineer(s) was/were and to what extent Page was actually involved. The Page hi res remasters were, per Page, all treated with some degree of EQing.
If you really want to make a trip down the rabbit hole start reading various forum discussions of which were the best Hendrix CD masters!