I didn't see a thread concerning this, so I thought it might be a good idea to put this list together.
I used @JonUrban's WEA Group Records Checklist page as a starting point: QuadraphonicQuad - WEA GROUP Records Checklist
It appears that these titles are no longer under the ownership of WEA/Rhino so these are titles that would not be released as Quadio Blu-Rays:
Black Oak Arkansas - Raunch n Roll (confirmed by @ForagingRhino)
Allman Brothers - Eat A Peach (5.1 SACD released by Universal)
Allman Brothers - Live at the Fillmore (5.1 SACD released by Universal & Complete Fillmore East Recordings released in 5.1 surround on Blu-Ray by Universal)
Mothers of Invention - Overnite Sensation
Frank Zappa - Apostrophe
Bob Dylan - Planet Waves
Frank Sinatra - My Way
Frank Sinatra - Old Blue Eyes is Back
Frank Sinatra - Some Nice Things I’ve Missed
Frank Sinatra - The Main Event
Bill Wyman - Monkey Grip
Eric Clapton - 461 Ocean Boulevard (4.0 Quadraphonic mix reissued by Universal on Blu-Ray as part of the Give Me Strength box set)
Eric Clapton - There’s One In Every Crowd (4.0 Quadraphonic mix reissued by Universal on Blu-Ray as part of the Give Me Strength box set)
Mike Oldfield - Tubular Bells (4.0 Quadraphonic mix reissued by SDE on Blu-Ray as part of the SDE Surround Sound Series)
So as you can see, not a very exhaustive list, so still plenty of good potential titles for Rhino to explore and reissue as part of their newly revitalized Quadio series
I used @JonUrban's WEA Group Records Checklist page as a starting point: QuadraphonicQuad - WEA GROUP Records Checklist
It appears that these titles are no longer under the ownership of WEA/Rhino so these are titles that would not be released as Quadio Blu-Rays:
Black Oak Arkansas - Raunch n Roll (confirmed by @ForagingRhino)
Allman Brothers - Eat A Peach (5.1 SACD released by Universal)
Allman Brothers - Live at the Fillmore (5.1 SACD released by Universal & Complete Fillmore East Recordings released in 5.1 surround on Blu-Ray by Universal)
Mothers of Invention - Overnite Sensation
Frank Zappa - Apostrophe
Bob Dylan - Planet Waves
Frank Sinatra - My Way
Frank Sinatra - Old Blue Eyes is Back
Frank Sinatra - Some Nice Things I’ve Missed
Frank Sinatra - The Main Event
Bill Wyman - Monkey Grip
Eric Clapton - 461 Ocean Boulevard (4.0 Quadraphonic mix reissued by Universal on Blu-Ray as part of the Give Me Strength box set)
Eric Clapton - There’s One In Every Crowd (4.0 Quadraphonic mix reissued by Universal on Blu-Ray as part of the Give Me Strength box set)
Mike Oldfield - Tubular Bells (4.0 Quadraphonic mix reissued by SDE on Blu-Ray as part of the SDE Surround Sound Series)
So as you can see, not a very exhaustive list, so still plenty of good potential titles for Rhino to explore and reissue as part of their newly revitalized Quadio series