Check out the miniDSP "in a box" from DSP4YOU. They're in Hong Kong so its about $40 shipping but they are tiny units using USB (use a cell phone charger for powering after programming) for power and PROGRAMMING. You can change crossover frequency, delay, phase and has many parametric equalizers all programmed with your computer. Super easy to set up. From what I heard they were started by three engineers seeking to provide an inexpensive DSP crossover with much flexibility. The unit that's in a box rather than just a circuit board is about $160 after shipping to the US. I have two of them, one for the main channels and another for the sub and center.