I had the old Phonic Wireless speaker that went through a concrete wall 100 feet away but it is in the illegal frequency range. I purchased a new Phonic with the updated frequency but it drops out at 25 feet and eventually lost the signal.! I exchanged it and the new one did the same thing. I am looking for a similar setup. A small transmitter and receiver that does not run on batteries. i want to plug it in and not worry about how much battery power I have left. Any suggestions?