Correct, even though the back speakers are wireless, they still need power in the back of the room.
The other problem with Wireless, they work fine at mid to high sound levels. At 30-40% and under volumes, the backs will constantly be kicking in / out of sound. i.e. Softer parts of the movie, ala wind at the back, rain, the sound will go off and then on with more solid rear sound, unless the volumes are cranked up.
In the end, the room I had mine in, was not closed off, so watching something in the middle of the night, with the family in bed got tiresome. So I just ended up wiring the rears and running the cables behind skirting boards.
Once I wired up the rears, I was much happier and I suupose that's the beauty of Wireless, there's that flexibility.
For the price and what they are, they are quite decent and I am surprised in the quality of sound they put out. The Accusounds were my first foray into Surround Sound.
I still have my Accusounds from 2.5 years ago, just have to get off my lazy backside and sell them.