I mainly use my PA3X at home, every few days or so.
Is it better to leave the rear power button on, so that the battery stays charged?
Or should I leave it off, and just turn it on when I am going to use it?
Thanks!

I leave it on, except I unplug it when there is a threat of lightening. Doesn't hurt to leave it off though. If the battery runs down it just takes a few more seconds to power up.
DonM

Thanks.
Does it kill the battery by keeping it constantly connected?

No, it doesn't.

The best thing about the internal battery is the clock (which now works) No need for a watch or reaching for your phone during a set. Just hit the screen and you know when breaktime is!

You take BREAKS ?!?!? ...

Oh yeah. Like clockwork in most cases.

Thanks!

Does your Korg have a hard drive in it (spinning disk type)? If so, I'd say power down if you aren't going to use it for a few days. You will extend the life of the drive...

And, do you have it connected to a good UPS (battery back up power)? Allowing it to brown out or get power cut due to a power outage is VERY bad for electronics.

All in all, if you are only playing once every few days, I'd say turn it off when not playing it.