If you want to turn the TwoBandStereoEQ example into a "hello world" without actually digging through the interrupt code, here is where the audio processing happens within the interrupt handler (in main.asm):

    ;Process Left Channel   (left input sample is in a)       

        move    #>Switch_1,r6           ; point to x:mem (switch states)

        move    #>Filter_1_K,r4         ; point to x:mem (coefficients)

        move    #>Filter_1_A_Left,r3    ; point to y:mem (filter mem)

        bsr     TwoBand_EQ              ; input in a, output in a

        move    a,y:LeftOutput

    ;Process Right Channel  (r6 is currently pointing to Switch 1)        

        move    y:RightInput,a          ; load right input sample in a

        move    #>Filter_1_K,r4         ; point to x:mem (coefficients)

        move    #>Filter_1_A_Right,r3   ; point to y:mem (filter mem)

        bsr     TwoBand_EQ              ; input in a, output in a

        move    a,y:RightOutput

The simplest pass-through example is to replace the above code with:

   ;Process Left Channel 

       move y:LeftInput,a

        nop ; replace with left audio processing

        move    a,y:LeftOutput

    ;Process Right Channel        

        move    y:RightInput,a

        nop ; replace with right audio processing

        move    a,y:RightOutput