The simplicity of Sansui's circuit still amazes me. Connect the resistor between the two emitters and the signals mix in phase, but connect it between the two collectors and you get out of phase blending. I had to scratch my head a bit to see how that works. I still like Scott's original pre-synth design, it could blend all the way from mono to L-R/R-L. Possibly a more practical version would limit the blend ratio to .414 at each extreme setting. A centre detent pot would be nice to indicate no blend then no switching would be required.