I had a problem the last time. When i had the volume on normal ingame, the sound is extremely loud. I dont know if that has to do with the part where the ambient generic might play it through every single speaker at the same volume. At 7.1 this means 3x as loud as usual. But this made it a pain to play the map as i had to turn down the volume of the game. For the skybox thing. i see alot of brushes creating the pattern, wasnt it possible to get the same effect with a texture? For the nav to prevent a team from walking in you could potentialy use a respawnroom visualizer which would keep the bots from ignoring the area without interupting regular players. It however doesnt make the nav exclude the area from having a nice edge at the brush so nav_split might have to be used to cover that. This is the normal way how valve excludes bots from reaching certain areas in mvm maps as it works exactly as a nodraw brush to them. A trick like this might be able to solve the clipping on the speaker. The "dad, oh my god" (which if i remember correctly is in the map) part comes from https://www.youtube.com/watch?v=WSeNSzJ2-Jw (at 39s you get that line).