Sounds like something is trying to decode the audio, rather than just pass it through, and is failing.
To be clear, though, if you want to bitstream, you DO want to enable Bitstreaming in Options -> Video -> Audio for Video. No ands ifs or buts. The static issue is something else, probably something misconfigured in the Audio Decoder you've selected. If you are just bitstreaming straight through, there is no reason to use anything other than the Red October HQ default because it works fine. Just leave that out of your self-configured filters, if you're adding anything manually. Does Bitstreaming work right if you just turn on Red October HQ by itself (without additional filters)? If so, then something you are adding is breaking it. If not, then we'll probably need more info about your setup.
Red October HQ doesn't choose madVR just as a temporary thing. There was a problem with madVR that madshi needed to fix (and did) and so they stopped using it for just a few builds. madvr should return as the Red October HQ default in the next public build. So, I'd probably just wait on that for the next build of MC to fix it on its own, and let it use EVR for right now.
So, the main thing you need is to get LAV CUVID working. This shouldn't be too tough, as I know a bunch of people here use this filter who have Nvidia cards. What happens if you configure Red October HQ, and then JUST add LAV CUVID to the Other Filters section for a particular file type?