The phase-shift occurs at frequencies far above the frequencies of hearing.
What are you trying to do?
Well I want to phase shift the audio of 7 tiny speakrs(between 20 to 50uS)which are side by side.
If you change R5 to 4.7k then the input DC voltage to the opamp will be only 0.54V.The opamp input and output can't go down that low and will cause severe distortion.
I think the power amplifier doesn't work when its input is +6V, it needs its input near 0VDC. So a coupling capacitor is needed to its input from this circuit. The input of the power amplifier also might need a resistor to ground.
Post the schematics with part numbers of the small pre-amplifier and the power amplifier and we will be able to see why the whole system doesn't work without anymore of this guessing.