Hi,
I had never even heard of quad, but I did have a DTS/5.1 system for home theater use and even before that some HiFi VHS and Sony 8mm video deck for concert videos etc. It never occurred to me that music would have been mixed in anything but 2.0 Stereo and mono.
Then I visited a friend from Nottingham UK when he was living in London, England. He played me a copy of the Q4 tape of Sabbath's Paranoid!
And after that I think a similar copy of ZZ Top's Tres Hombres. I got 5.1 DVD-A copies from him and I was hooked. Later I found out that I actually had (inherited) and bunch of surround stereo LP's, I had never thought about that "SQ" logo. So I got (again thanks to the same friend's recommendations) an Involve Audio Surround Master for home use, and then luckily found an old AKAI 630D SS reel-to-reel and started searchig for a 4-ch receiver/amp.
Being a sucker for design I ended up with Bang & Olufsen's BeoMaster 6000 (Typ 2702) wit the CD-4 capable Beogram 6000 and vintage speakers (4702 and S45-2) as well as later getting an Audiovox Q8 Stereo radio system from 1975 for the 1975 Jaguar XJ coupé and an AKAI CR-80D SS Q8 tape deck for home use!
I'm still in the infancy, planning to make both digital (4 channel 24/96) and analog (7 ips 1/4" tape) copies of the Q8 tapes I've got, as I know car use can eat them up! (I already destroyed last summer the Quincy Jones "Walking In Space" Q8 that I DID NOT yet have a backup or copy of.
The only Q4's I've got so far are the Vanguard's Country Joe & Fish and WB's Frank Sinatra's Greatest Hits Vol.2.
And the only CD-4's I have are Frank Zappa's Apostrophe and The Doors' Greatest Hits.
Q8's I think I already have about thirty and counting.
But it's been nice to get DVD-A's and SACD's and other stuff that either has the old school 4.0 mix or copies of the Q4's and Quadradiscs on tape or DVD's.
Deep Purple, Jethro Tull etc.