I have my PSW505 set to automatic; it's supposed to power off after 15 minutes. I've noticed the red light behind it is always on. Does this mean it is not powering off...or does it just stay on all the time? How do I know if it is actually switching to standby mode or off mode? Should I still unplug it when I am away for a long period of time....even though it supposedly switches off with no input signal detected? Thanks.