I've got a new cardio machine. I want to listen to the TV while on it, but I have to turn the TV up way too loud to hear it. I want some kind of doo-hicky I can plug into my stereo (where my TV noise passes through) and transmits to my machine where I can plug my normal workout headphones into it. Anyone know a good product to do what I'm looking to do? Battery power is fine by me, but I can plug something into the wall if necessary.