I am using the TIP31 because it initially made it extremely simple to amplify my audio signal to 0v-5v.
I am not driving a matrix, it's just a bunch of LED's in parralel.
It's also completely analog, so no Arduino (yet).
Simply put, I just need to know how to make a (pre)amplifier circuit using either a TL802 opamp or some 2N3904 transistors.