message: Comment out SD
diff: #if defined(KINETISK) //only include these for Teensy 3.x (and not Teensy 4)
  //include "input_i2s_quad_f32.h"
  -#include "SdFat_Gre.h"
  -#include "AudioSDWriter_F32.h"
  -#include "SDWriter.h"
  +//include "SdFat_Gre.h"
  +//include "AudioSDWriter_F32.h"
  +//include "SDWriter.h"
  //#include "USB_Audio_F32.h"
  //include "output_i2s_quad_f32.h"
  #endif
  