Can I use four Remotes with one Receiver?

Unfortunately, it is not possible to use one Phase Receiver with four decks simultaneously, even if you own the Ultimate edition. This is due to the fact that Phase only have two audio outputs. 

It is hence impossible to use Phase with four turntables simultaneously. 

You can use Phase to control 4 decks at the same time, but the only way to do so is to use two Receivers, and four Remotes.