Let the hive mind of Engadget get that for you.
"I am looking for a device that will stream sound from one source to several recipients. For example, I want to stream sound from my TV or stereo to my phone or MP3 player that has radio and Bluetooth capabilities. I have looked into radio transmitters and they seem like a decent choice, but I can't find one that uses external power (USB or from the plug) and I would want one with a transmit range of around 50 meters. Thanks!"
The amount of space the HD signal takes up depends on the modulation. If your cable company is using 256 QAM, they can actually fit two HD channels in the space of each analog. If they are using 64 QAM, they can only fit one. I'm not sure about other modulation types, but most cable companies are migrating toward QAM if they're not already there.
Basically, a lot of problems will just go away along with analog :-)