Can I purchase a second wireless receiver for the rear speakers?
The rear speaker wires are not long enough to connect to one wireless receiver for optimal placement of both
speakers. A second wireless receiver would provide the flexibility needed
No you cannot but, if you place it where you can, you can go to sound settings and make the volume higher or lower to what you need and make it sound as if the speaker was further away. Or if you are are a little handy you can buy some speaker wire, cut the stock wire in the middle, solder the new wire to the old to extend, the heat shrink the soldered area and then you could have the speakers as far as you want. Its pretty easy if you're careful. Just make sure to solder positive to positive and neutral to neutral.