One easy way to try this out is to get one of the newer class D Crown XLS stereo amps with the DSP crossover (xls1502 is a sweet spot). You can pass it a mono signal from a pre-amp pedal and set the crossover wherever you want, driving 2 speakon outputs (lo and hi). Warning: your ears may be permanently spoiled. I've moved on to full 2-band mono processing starting at the preamp stage, but that was my proof of concept setup. If possible dial any tweeter on the low end cab all the way down (otherwise it'll just be adding hiss).
