There are two types of bass nobs you could get with an amp, first is a gain nob which Is useful and does basicly the same thing as a RCA level. The other is a bass boost nob wich you should NEVER use. It will only lead to clipping. If you have one of those. Use a RCA level
Very true! Impedence rise is a big problem with passive xovers. More wire would just ad to the effect. And it would most Likely screw with the xovers zobel circuits with more wire.