Great that it sounds, well... great!
I think it must be normal it coming from the speakers connected to the receiver. Not sure why it wouldn't disable the connected speakers though. You can get stereo amps that allow 2 sets of speakers to be connected, that allow you to disable one set. Others though, only let you use 1 set, or both. Might depend on the manufacturer maybe, how it's done.
No idea about the part mode. Might have a nose at the manual later, see what that's about.
I think it must be normal it coming from the speakers connected to the receiver. Not sure why it wouldn't disable the connected speakers though. You can get stereo amps that allow 2 sets of speakers to be connected, that allow you to disable one set. Others though, only let you use 1 set, or both. Might depend on the manufacturer maybe, how it's done.
No idea about the part mode. Might have a nose at the manual later, see what that's about.