You experienced Quad masters here certainly understand the whole SQ thing far better than I ever will; always interesting to read these insights and ideas about it. It’s just a mind blower for me that a musician of Santana’s caliber (along with many others) end up with such trashy sounding versions. Could it be some of these engineers tasked with working with Quad back then just didn’t know the equipment/mixing techniques well enough to do it justice. I’m still amazed at how some SQ titles sound fairly decent, while so many are just a real mess. But this was 1976, pretty late in the Quad game right?
Fred Catero knew full well how to mix music into proper discrete Quad, for some reason he stopped doing so after 1975!