audio electrical info

[adam]

Hi.  How do audio signals work?
I understand that voltage=volume, freq=freq...

But how does impedence fit?

i.e. what is the difference between a line level signal, a mic signal, and
one that goes to your speaker?{be specific if possible - what is the
nominal voltage PP(i am assuming the means peak to peak) for each.}

furthermore, how do i safely attenuate a say a line signal down to 360mv PP,
then after running it through a chip get it back up to line level (with
minimal noise)

thanks
adam.

ps. thanks to all the people responding to my powersupply question.
the solution i found cheapest was to use on of my many existing +15v
supplies.  Split three ways with voltage regulators for +12 and two +5. Then
using a dc-dc convertor to make one of the +5's a -5(i didn't know such a
device existed until i found one at the local electronics shop{$1.99cdn}).
I will likely get a good bench supply.  But this is a handy way to get
multiple voltages (with opposite polarities) out of an existing wall-wort.