Yep, VCAs are the missing things here. Consider adding some for audio and CV/modulation, given that you want that sense of gradual shift/flow with that sort of music. I'd suggest something that can break up the two different functions while also providing mixing, such as Happy Nerding's 3xVCAs. At 6 hp, they're small enough to fit in nicely, and they allow you to separate two mixed VCAs from a separate one in case you need to split up the VCAs' functions even further like that.