In that case this means that there is an issue with the app, perhaps a bug. Bitstream should sound exactly the same. If it doesn't sound the same, it's a software bug or misconfiguration. Component quality has nothing to do with digital audio or video.
And if firestick sounds bad, Nvidia shield will too since both use the same android apps. This is why I'm actually considering buying the Apple TV 4k over the shield, as some software things are just way better in tvOS like refresh rate switching and colour gamut handling.