Gain is a measure of the output signal divided by the input signal. It can be a ratio of output/input voltage, current, or power, depending upon the application.
If the gains are not close when used for bi-amping, then the tweeter and midrange/woofer volume levels will vary relative to each other as the overall volume changes. I have never tried this but I would think it would be somewhat disconcerting to listen to. It should be OK if they are at least close.
If the gains are not close when used for bi-amping, then the tweeter and midrange/woofer volume levels will vary relative to each other as the overall volume changes. I have never tried this but I would think it would be somewhat disconcerting to listen to. It should be OK if they are at least close.