said by doncoolio:
I have the same the same ability on two receivers. They both pass through every other device I own. I would consider this a STB thing.
I have a Yamaha RX-V667 and audio and video pass through with the reciever off with out issue. You may want to look at the settings in whatever surround sound "reciever" you are using or check its owners manual to see if it will pass through audio and video while tunred off.