So we were pretty bummed in our early testing of Amazon's newly HD-enabled Video On Demand service to find that it only streamed stereo audio instead of full 5.1 surround, but it looks like that's actually device-dependent -- we just tested it out on our TiVo HD, and movies play back in Dolby Digital 5.1. Yeah, that's still no Dolby TrueHD or DTS-HD, but it's definitely a vast upgrade from the sad two channels we got off the Roku Video Player. So why the difference? The TiVo doesn't stream content like the Roku -- it actually downloads a video file and plays it locally from its hard drive. That means that in addition to surround audio, we also saw a pretty dramatic increase
