Volume control noise
Hi Stanley,
I was probably not clear enough. I was suggesting connecting the lower or ground terminal of the volume control to C205. The idea is to feed the bias voltage back up the volume control to the inverting pin and thus remove the need for the C204 isolation capacitor.
This amplifier can be thought of in terms of an op-amp. Op-amps with negative feedback have a property called a "virtual ground" between the two input terminals. What this means is that the op-amp will adjust itself at all times until the voltage at the inverting input exactly matches in voltage at the non-inverting input. With a DC bias on the non-inverting input, the op-amp will require this same voltage on the inverting input. Hopefully, by feeding this voltage back through the volume control, the coupling capacitor can be removed.
C205 provides an AC ground for the audio frequencies, so to the incoming audio, then volume control still appears to be connected to ground.