Laser diode module and audio amplifier tia sal2

Greetings All

I have a laser diode module with the datasheet of
output 5mw
wavelength 640-660nm
that is powered by 3Vdc I've created a simple laser communicator
following the instructions from
this site http://sci-toys.com/scitoys/scitoys/light/light.html


This works great but I was wondering if I
could power my laser module using just the output of a cheap audio
amplifier (like from radio shack) and not use the transformer
if so what calculations and changes to the circuit
would I need to make to prevent destroying the laser.

Tia
Sal2