Hi - the Marantz doesn't have wifi (only Airplay, which doesn't help with an Android table), but it does have Ethernet. Is the Marantz close enough to your router to plug it in via cable? If so, it will spot the server running on your PC (yes, it does need to be turned on) and hook up to it.
If you're not close enough for a wired connection you can add a wireless extender for about £20 or use Ethernet over mains with something like Homeplugs.