How do you match the amps output? How do you split the audio signal into
both amps? If there is a good article on the whys and hows please point me!

To split the audio signal, take the signal from your preamplifier into
an electronic crossover. Set the crossover value to whatever you want.
You should take two outputs from the crossover, one for each power amp.

Then if you have two separate unmatched amplifiers, you will have to use
a second volume control for the second amp, called a passive level
control. This is sort of like a stunted preamp, and doesn't affect the
sound.

Biamping is like putting a subwoofer into your system. Most every one
is "biamped" with the mains these days.

-Sean