Re: Audio amplifier
First: select the IC.
Second: calculate supply voltage .
In case of normal push pull amplifier (not bridge amplifier, supplied from one voltage and with capacitor coupled speaker) the voltage on the speaker to get needed power is:
U=sqr(P*R) in you case it gives sqr(1.6) = 1.3V
this is a rms value , so it should be multiply by 1.42 to get a peak value (in case of sinus at the input) .
This should be multiply by 2 because the sine changes from positive to negative. (For zero at input you have 1/2 supply voltage at output).
At the top of it you should add a voltage necessary on each output transistor as to proper work (the exact value is given in IC application note) .
If this "per transistor voltage" is 1V you will get the supply equal 5,6 Volts.