Just ask yourself, "Do I want to be smart about this? Or do I want to be an audiophile?". That should guide you in the right direction. It's easier to add than subtract. If they see it, they want it --- even if they don't really want it. Best to empty everything out of the place - everything - before you list.
Then, as a contractor, you can furnish anything they want at an additional charge. Otherwise, if it's in the building, they will probably try to muscle it away from you or, at the very least, leverage the price down due to exclusion. If the room is prewired, that's a selling point.