Being overly practical (and financially honest) I started out with a Q8-track system in my car around '74 (I think). At the time it was the easiest way for me to do quad. I was doing much of my listening in the car as opposed to at home at the time. Also, after reading a lot about the format I was convinced that, for me, Q8 was the way to go as the matrix systems were not true discrete 4 channel sound. The deck I bought was put out by Clarion (with some relationship to Muntz). It was an underdash and the install was quite easy. I had a '72 Charger and just needed to install speakers in the kick panels up front. I had the local stereo shop do the cut outs and install of the Jensen coaxial 5 1/4" speakers which 'just fit'. I had previously replaced the factory 6X9's in the rear deck with coaxials (possibly Jensen or R/S). Put back boxes, which were a new thing at the time, on the 6X9's to improve the bass (I don't like 'cliche boomy' car sound, prefer a more balanced presentation). It sounded great!
Don't remember what was the first tape I bought, but I ended up with a bunch of stuff I liked - Walls & Bridges, DSOTM, Iguana's Winds of Alamar, Blow By Blow, Road Food, On the Border, Tea for the Tillerman, Question of Balance, DOFP, Court & Spark, Apostrophe, Stampede, Capt. & Me, Hearts, Holiday, Allman Bros. Live album, 421 Ocean Blvd., Supersession, All American Boy, several Tomita albums, Myths/Legends of King Arthur, Can't Buy a Thrill, Mysterious Traveller, Nilsson Schmilsson etc. Most were quite good, a few disappointing.
I got a lot of my tapes from a little newsletter/catalog that stocked quite a bit of what was available on tape and vinyl in whatever quad format you might want. They also had a section where folks could post quad related gear for sale. From that I got a used Pioneer QH-44 deck for the house. I also picked up a Dynaco Quadapter, which separates out the out of phase sounds and channels it to rear speakers, from another seller.
Around that time (80's), Carver had come out with some gear that introduced a delayed, out of phase version of the audio and cross panned it (don't remember if this was just an amp/receiver or speaker system or both). The idea was, for example, that you would have left channel audio accompanied by a separate driver with out of phase and delayed right channel audio coming from the same speaker. The delay matched the delay of an average human's HTF. I put together the poor man's version by placing a Minimus 7 on each of my speakers, set them back around 8 inches from the front of the cabinet for the HTF delay, left was right/right was left and wired them opposite phase wise to the main speakers. It definitely produced a larger and more immersive listening experience. My one error was I used my Kenwood's A+B speaker choice to do this which made the impedance too low for safe operation of the integrated amp. After several years the Kenwood quit working which was my own fault having intentionally used the setting and the resulting impedance issue.
As things have changed, I no longer have a music set up at home. Any listening I do now is in car and I'm not doing as much of that as I used to. It's gotten to the place it's so overwhelming with all the great stuff out there, I stopped trying keep up with it all. I read what you folks post here and wish I was 25 again with disposable income. Lot's a great music out there. Enjoy!