I recall years ago having either a woofer failure or a loose wire, I was amazed that I didn't notice it at all at first. One time I was toying with the idea of separate woofers and mid/tweeters mounted in separate enclosures. That experiment showed that the drivers had to be placed close together or they didn't sound right at all.Agreed but the common bass signal typically cancelled out L-R so the rear speakers really did not need to be full range making the technique suitable to the satellite speaker concept. A good reason to make bass common in recordings is to get the benefit of 2 sets of drivers working together to push enoigh air to extend the bass, in addition to the wrong myth that bass is non directional below 150 Hz . Our tests showed that on sine wave pure tone bass is actually non directional to 800 Hz but on band limited pink noise was totally directional down to 35 Hz!! Explains why I can always point to where the subwoofer is for the first 30 seconds before my brain masks the position.