Is it possible to use single-supply amps throughout?

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Yes, but you'd have to use caps on the inputs and outputs and
reference the opamp + inputs to Vcc/2.
[J. Fields]

Only a single supply (in the amplified speakers) is available to power this
circuit. I can tap this supply for my circuit:

http://i41.tinypic.com/2vlo2t2.jpg

I've added input & output caps. Are these values sound? ;-)

How do I go about getting a 1/2 Vcc ground reference? (See my non-EE
attempt.) What values to use for the divider resistors?

What needs to be reference to the new "ground"? Everything between the input
caps and output caps?

Thanks,
Dave