If you have preamp outputs and amp inputs, you can use this inexpensive device to act as a very configurable electronic crossover: Dayton Audio DSP-408. Get the Bluetooth dongle with it. I hear it’s sound can be improved by using a 15V power brick instead of 12V supplied, but I haven’t tried it myself. This unit is pretty geeky, so if you are not so inclined, pass, but the same is true for miniDSP. If you want an analog crossover with this kind of flexibility, JL Audio makes the CR-1, but it is not inexpensive!