Why is my UVerse sound so low?

[robocopywriter]

I watch movies outside with a projector and outdoor speakers on nice nights. Everything is great. I also use the system with an Archer amp to stream my iTunes library to the yard. That works great. If I turn the volume past half, neighbors across the street complain. Now the issue. Tomorrow is the last episode of Battlestar Galactica, so I want to have friends over and an outside party. I've never watched live TV, just DVDs. So I ran a coax from the kitchen UVerse box to the an old VCR outside and connected a the projector to the VCR. Picture was great, but the sound was almost non-existent. Turned the Archer up to 10 and, if I didn't move or make noise I could hear it. When I pulled the RCA jacks the sound was deafening, When I put them back in nothing? Something is constraining the volume out of the UVerse box. Any ideas? Galactica starts at 9pm on Friday. Thanks in advance.