If you are using bi-amplification without active crossovers ahead of the amplifier and are still relying on the internal speaker crossovers, then any attenuation that the loudspeaker manufacturer built in to the crossovers, in order affect the ratio of signal sent to each driver, still remains in the signal path. Sending one amplifier channel to the woofer and another amplifier channel to the mid and/or high frequency drivers through the original crossovers merely requires that both channels have the same amount of gain/output – unless you are using channel gain as a substitute ‘tone control’ in order to create a different ratio than the manufacturer intended.

While idealistically I prefer active crossovers ahead of each amplifier channel and the elimination of the passive crossovers, the implementation of such a system is much more involved, technically and financially.

I use unbalanced runs, generally of 2m or less, without problems. I use longer unbalanced runs, about 5m, to powered subs without problems as well. Most of the interconnects are constructed of a rather high-quality commercial cable, Belden 1694A. A few cables, for the rarely used VCR, are RS next-to-best grade.