UNITY GAIN VS 4 PIN DIN INPUT

Hi All. I have been using my Nait 5 as a poweramp with an external preamp. I did not have a 4 pin din plug handy, so have been using Unity Gain via the AV input. Should I expect any difference in sound using the 4 pin input?

Can i cause damage to my Nait? I would like to leave it powered up 24/7. Thanks!