fungus:
There's about a bazillian pages on the web that tell you how to use an op-amp to amplify a signal.Why a transistor? Why not use a chip that's designed to take an audio input and light up some LEDs?
eg. AN6884, LM3914, etc.
The AN6884 even has a built-in amplifier....tada!
Like I said, they're what I have on hand. I don't have time to order/get new components.