I am looking into taking a stream of audio from a mic, through the ADC, out to Serial Port, back in through the Serial port, through the DSP core and then out to the DAC. I understand that 38 uS (or 76 uS when running at 96kHz sampling rate) end-to-end delay can be achieved with just a "pass through" on the DSP (and I was able to measure and achieve that with my setup on the EVAL board), but I want to include sending out the I2S port and getting audio data back. So far, an audio pass through program on an ARM M4 processor over I2S gives me 200 uS delay when running the ADAU1772 ADC at 96k, and the Serial port also at 96k. I understand there could be latency involved in my processing, but I wanted to know if the ASRC is contributing to this delay. Also, should there actually be any sample rate converting at all if the sample rates across the board are the same?