The paper investigates the parameters affecting THD and PSRR in a PWM class D amplifiers with feedback. From our mathematical analysis, the authors show that the THD and PSRR of a PWM class D Amplifiers with feedback can be improved by shaping the frequency response of the 2nd-order integrator. The paper also shows how the THD can be further improved by means of dual-loop feedback. Simulation shows that the THD of the single-loop and the dual-loop feedback class D amplifiers can be improved by as much as 3 times and 12 times respectively