not being unnecessary/awkward, i'm fascinated and genuinely unclear how QS variomatrix and/or Involve could accurately extract more in their decoding process(es) than an EV-4 decoder with source material that's surely limited by the original EV-4 encoding?There is no point in using an EV-4 decoder. That decoder was little more than an active version of the Dyna Quadaptor. The decode coefficients didn't even match the encode ones. It was designed to give a good surround effect with stereo records. It was designed purely subjectively, doing a good job for it's time.
QS Vario-matrix and Involve will extract far greater separation than the original Stereo-4 decoder.
MidiMagic has even suggested moving your chair farther back in the room to hear the correct perspective. The fronts will decode a bit more toward the sides while the backs will be a bit closer together.
seems like there's nothing extra there to gain, you can't get a whole pint of milk out of a half pint pot! unless i'm totally misunderstanding what's being suggested