The OPN start-up tune (for those who haven’t experienced them, OPNs play not just a couple of tones but a whole tune of about 20 or so notes) is rather annoying since it goes on for a while. I’ve taken to just turning them on before I’m putting them in my ears, waiting a few seconds for them to boot up and play the tune, then putting them on. I don’t need the tones to let me know they’re on … I can tell that right away as soon as they’re in my ear because I can then hear the HVAC running, the fridge running, my dog walking across the floor, etc. Before I got the OPNs, BuyHear had me test a pair of Widex Beyond. Turned those on and, after they had a couple of seconds to boot, they’d say “right ready” and “left ready”. That was much better, in my opinion.
Re: the boot-up delay … given that these things are essentially little computers, having some delay from powering on to being ready to put sound through the system seems more than reasonable to me.