Replace analog pot with digital - volume control
None of the 'pot' pins can be allowed to go (much) beyond the power supply voltages. 

If you have a digital pot with 0/5V supply you need to keep the voltages within that range. Since you are dealing with audio signals, they are AC, and you could bias the input at 2.5V with a couple of resistors and your coupling capacitor, so that the analog input (and output) sit at +2.5V (thump on start-up). Or use +/-2.5V supplies. And make sure you never get too much input amplitude or you could destroy the chip.   

It's often not that easy to replace a pot with a digital pot in an existing circuit- you end up redesigning.

There are some digital pots (eg. AD7376) that will work with relatively high and bipolar supply voltages, while retaining digital inputs referenced to ground but they tend to be relatively expensive. Depending on the function, you might also do much better with a log taper digital pot in an audio application.