A few manufacturers of some devices have included IR commands (not on the original remote) that do horrible things, such as erasing the firmware that the device needs for normal operation. It isn't common. I don't recall any stories about Onkyo ever doing that (though my memory should never be trusted). I don't even recall any stories about such problems with any brand of receiver. Most such stories are about TV's. But it is still a risk that you should evaluate for yourself.


What about the signals Peter suggested?

Onkyo is pretty consistent in IR signals across models. Once someone has identified useful commands in one model, those are both safer and easier to test in your own model than trying the whole set of 512.

Within the same brand, I've never heard of a command being a useful discrete in one model and destructive in another. That would really be an insane thing for the manufacturer to do, since multiple models tend to be present together in the higher end stores where discrete signals are likely to be used to manage them.

Across brandss, the worst I've heard of is a TV whose self destruct command matched the PIP command of TV's of other more common brands.