Explorer Notes and Broth of Enlightenment

I've been searching around for this info, but I can't seem to find the answer. I can open explorer notes and get up to an 8x xp boost. If I also consume a broth of enlightenment, does it stack as well? If it does, is it additive and I get 8.5x? Multiplicative to get to 12x? Some other amount? I'm trying to figure the best way to optimize some Aberration spino killing.