The diffusion synthetic acceleration (DSA) method is an iterative procedure for obtaining rapidly convergent numerical solutions of discrete ordinates problems. General PL acceleration methods for L>1 are first considered to determine if DSA, which is equivalent to P1 acceleration, is optimum. After determining that DSA appears to be the optimum PL approach, it is then demonstrated that by also using standard techniques of matrix iterative acceleration, modest improvements can be made in DSA performance.