My second Vizio. First one had a hum from top rear of set. This one has a hum from the speakers on the front of the set. No hum from 5.1 speakers. No hum if I disconnect the lines leading into the Vizio speakers. Tried different AC outlets, no joy. Home is new, grounded outlets. Anyone else having this trouble and what was your solution? Last resort will be to take it back and get a third one.