Hello Mitch4T! If you want it with fixed frequencies, use one of the units from miniDSP. If you want to play around with the crossover points get a DBX unit (like the 223 - different kinds of connectors on different units) will let you have fun trying different crossover points. I have (and am using) 4 miniDSP and 3 DBXers. Great stuff!
Enjoy, Boomer Bill
Enjoy, Boomer Bill