i dont understand what DXNewcastle mean about "It is because there is NOT a capacitor to block DC between the potentiometer and the buffer amplifier"
In your circuit, the DC conditions on the non-inverting input (Pin 1 of U1A) are grounded via the potentiometer.
0 volts on the non-inverting input will produce 0 volts on the output.
So, any audio signal will be an AC signal superimposed on the static DC condition of 0 volts. That would, for example, be a small signal with instantaneous voltages in the range between +2 volts and -2 volts.
The pre-amplifier will be incapable of producing that AC signal at its output becuase it does not have a power supply which provides negative voltages. It could only amplify the positive half-cycles, and even these are going to be poorly controlled close the 0 volts supply voltage. As Betwixt stated, the pre-amplifier will only be capable of producing extremely distorted audio.
If you had a reason to put a pre-amplifier before the power amplifier, then its DC must be biased to (approximately) half the suplpy voltage.
But the point I was trying to make to you was that a designer would only include a buffer amplifier into a circuit if it was going to achieve something useful. In this case, it has no purpose.