tim c: Bridging is combining the left and right channels to one channel and the end result is a single (mono) channel with twice the power.
Vince: There is a way around this though depending on the kx650.4 inputs. Does it have 2 or 4 channel inputs? If 4, it can be done, just run your left side to 1 & 2 and right side to 3 & 4 out of the head unit and make sure the amp settings are properly selected. If 2, your amp must have a setting to have #1 input feed #1 & 2 output and #2 input feed #3 & 4 out.