Electronic Crossover recommend

I have used electronic crossovers on and off for almost 40 years, but I just recently tumbled to the realization that there is no one correct X/O frequency for the SW/Main transition, even for a particular audio system. It depends on the music you are playing. Therefore, whatever brand of X/O you select, make sure it is one that has the frequency easily changed by a knob. Units that determine the frequency by means of a plug-in module are simple and reliable, but constrain what you can get out of your system.

Knowing the rest of your system would give us an idea as to the level of "highend" that you need.

If your corssover point is as low as you state here, can you even go lower? Just getting the bottom 2 octaves out of the main speakers makes a huge difference and this can be done by simply adding the appropriate capacitior on the input of the main amp; this acts as a first-order high pass filter. Then you can use an active low-pass crossover with level adjustment for the lower-frequency amp. This entire process keeps the main amp and speakers as clean as possible as it eliminates all the active stages and additional cables.

If you find that you truly need an active crossover to drive both amps, the PASS XVR1 would be at the top of my list.