I'm trying to run some ten inch subs on the b speaker input but I'm sure I need a filter to cut off the highs. Any advice? Thanks in advance.
can you explain? My brain is not workingManu, if you have extra power amps lying around, why not make a simple line level crossover (R/C network) and go bi-amp?
It's not necessary to buy an electronic crossover in order to have a true bi-amp system. You can make simple high-pass and low-pass filters that connect between your preamp and multiple power amps. There are online calculators intended for speaker crossover design that easily scale up to line impedance level, or you can work from filter cookbooks or published sources such as THIS.