This is my proposed layout for the active crossover/power amp, with its four channels of amplification using Hypex ucD180 modules (180w/4ohm 120w/8ohm). I have kept Left and Right separated, each side having its own Switch Mode Power Supply. The active "KMTech" crossover board for each side is powered by its SMPS aux unregulated output, so a small adjustable regulator board has been inserted for each crossover, to supply the required +/- 12Vdc. I have made provision for an adjustment pot on the Bass output of the crossover to match the bass driver to the mid/tweeter level. The mid/tweeter are 8ohm and only 84dB/1w/1m sensitivity, were as the Bass driver is 4ohm and 89dB/1w/1m. Using identical amp modules, the bass driver should have more output, but it requires more power than a mid/tweeter anyway, my gut feeling is it will still have too much and will require just a small amount of attenuation to match the less efficient mid/tweeter set up. We will have to see if that works out correctly. AC/DC/Signal lines have been kept apart to reduce the chances of interference.
The whole thing fits into a 2U x 300 19" rack case.