On Startup, Restart, Hot Plug, Firmware Update, Sample Rate Change medium volume pops and clicks can be heard in Speakers and Headphones.
This is common with all audio gear. However different units can have a different level of pop due to filters on outputs or the level of speakers after the output.
If it is an issue we recommend turning Speakers down or off and removing Headphones. Always good to observe standard LOFO or Last On First Off procedure.