I have an Xtant 403a, 2x50 1x125 @4ohm

I have it setup with a low pass on the 125W running @3ohms on a single 12" JL 12w6

and I have the ohm splitter module and a high pass module on the 2x50 to allow me to power all of my mains from the 2channel amp.. the only dis-advantage is that I don't have fader controls.. but it's balanced decently, so there isn't much of a problem.

I like the xtant because it has the internal modular slots on the line input, but they're built in so there is less cabling and less chance for input distortion. it also keeps the amount of wire-tangle down in the trunk.