funny. I just bought a Vizio 55" set myself. they lend themselves well to this application. They have an audio out and you can use the menu to turn the speakers off and use the output as either fixed or variable.
Offhand, I'd say this gives the best bang for the buck. One of these...
http://www.accessories4less.com/mak...00-watts-natural-sound-stereo-receiver/1.html
It's got four line level inputs, which ae quite handy.
and one of these.
http://www.parts-express.com/dayton-audio-sub-1200-12-120-watt-powered-subwoofer--300-629
You would use the speaker level inputs to the sub.
Actually, I just bought both within the last 6 months and don't regret it. I reviewed them both somewhere towards the end of this thread.
http://forums.audioholics.com/forum...-you-bought-if-you-care-to-share-thead.86935/
workin' great with the Vizio.