One other question about your idea of feeding the audio to the analog input of the arduino
I understand about the diode and its use but an audio signal is already pretty low power.
Wouldn't adding a resistor with the diode knock the power down so far that the Arduino would be able to use it?
I know I could use the serial monitor to display the values and adjust my code accordingly
But it still seems like it would be extremely low.
If i took the signal before amplification it would "really" be low,
and if I used it after the amp on the wave shield and adjusted the volume it would throw off all the values.
Am I correct or am I completely missing the mark???