I have an Acer Revo connected to an Onkyo 607 thru HDMI. I am running Windows 7 64. I am getting sound from my fronts center and sub but nothing from my surround speakers. I have it set up as 5.1 which is what i have. When i go to test the speakers in the set up when i test the rear speakers the test plays the sound thru the front speakers. Any help is appreciated. Thanks.