Quick rant about "group call theory" for chapter 4: it is retarded.
Why would the game go to great lengths to establish that Spamton had private calls with a mysterious benefactor over an old-ass rotary phone in both chapters 2 and 3, where third parties, even if they tried to listen in on it, could not hear anything but garbage noise? Only to later drop the idea of a "conspiracy group call" on the player's head?
It feels like an overcomplicated thought that absolutely does not pass Occam's Razor. In the overwhelming majority of cases in media, phone calls symbolize private 1-to-1 conversations. You have to make it very clear to convey the idea that there are multiple people involved.
Fuck the idea that Kris is contacting a "group", fuck the idea that "the voice is black because it's coming out of a Dark World". It's just more unnecessary complication.
The simplest explanation? The voice is black because it's the voice of the Knight, a singular entity who's a fucked up darkness monster that is 100% black, exactly like the speech bubble. The one individual Kris is clearly and obviously shown to be colluding with.