I had a 4 channel system; you need a 4 channel pre-amp, a 4 channel amp, and 4 speakers to get the full benefit of a 4 channel record; it produces something akin to surround sound.
https://www.google.com/search?q=phase+linear+4000&oq=phase+l&aqs=chrome.3.69i57j0l5.17975j0j...
You will also need a 4 channel amp
https://www.google.com/search?q=dynaco+qsa+400&tbm=isch&source=iu&ictx=1&fir=1kHUCYG...:
It was a system I enjoyed for many years. Although not high end in the sense I enjoy stereo high end today, it was fun.