Bi-wire v's single with jumper leads.

While the back emf from the LF driver does create a signal that beats with the higher frequency components to produce distortion in the range of the HF circuit, I question the extent of that signal. Thevenizing the respective circuits (with a signal sources from the amp and signal source from the LF driver) results in a large disparity in loads. Unless the output Z of the amp and cable are significant in comparison with the Z of the HF circuit the amount of IMD should be extremely small. Most decent amplifiers and just about any cable at length less than say 20 feet present a Z orders of magnitude less than the HF circuit. While biwiring will affect the IMD caused by the LF driver signal, it is unlikely that the IMD thus generated is of any practical signficance in most instances.

How do you figure the emf of the LF driver (essentially a source at that point) sees a Z of the cable and amp that is less than the Z of the HF circuit? It is not even close. HF circuits typically have a resistor in series with the driver ( 2 or 2.5 ohms usually), that series resistance plus the R and L of the HF coil swamps the Z of the cable and amp. Additionally, the frequencies supplied by the LF driver that will fall in the passband of the HF crossover are attenuated by the passive components in the crossover of the LF circuit, particularly if that crossover is higher than first order as part of that crossover will have a low Z path that shunts the higher frequencies.

Kijanki: I had misread your earlier post - you did indeed remark ( and correctly I might add) that the cable - amp Z was less than the HF circuit Z.