Hmmm weird, I can't see why a power supply would interfere with a controllers connectivity you never know though. Do you have anything else in the room that runs on a wireless connection? Bluetooth, routers, mobiles or CBs?
Even though the Xbox is hard wired there will still be wireless signals or it wouldn't get a wireless signal. Try turning off the router and any wireless items. Many people have been having some issues with there controller I am one of them but not to your
extent. So it could be a update that has done it, I'm sure a mod or a Xbox team member can confirm this? If all else fails do you have kinect? Maybe it is giving out dodgy signals unplug it.
If not then it may be that you were just unlucky and got two broken items.