QUIT / POWER OFF what's the difference?
tnx for any reply

Quit exits the player software and drops to the linux shell prompt. This is only useful if you are a software developer and have a serial connection to the player as described here.

Power off puts the player into Standby mode as described here.

Note that the Quit menu option is not activated by default. In order for "Quit" to appear on the menu, you would have needed to activate it yourself by setting that option in Emplode.