"Next to raw" food and stinky poo

Since we started the switch to higher protein food(using Wellness Core right now) I noticed the cats poo smells even worse than before. Is that normal? I thought maybe they are "cleaning" their insides....dunno. They have CORE still mixed with the left over Natural Balance(I would say almost hal and half now) and some wet morning and evening-brands vary since Halo eats pate style and picky pants Phoebe only gravy ones.....
Good grief it smells awful.....
(Poo has not been runny though, just fyi)

Wellness Core is a very rich food, and some cats can't tolerate it... my Kizzy being one of them. He loves the food, but he stinks, and it does give him loose stool (not diarrhea, but soft stool).

How long have they been eating the core? Perhaps try a lesser amount of core vs NB, untill you find a balance...then increase ever so slightly. Don't rush it though. Your kitties may not be able to handle the Core.... it does happen. (I give kizzy maybe a tsp worth of Core, than seems to keep his poo's ok).

Most premium grain containing foods have neutralizers ( often a prebiotic like beet pulp or chicory root to help with smell).. I second it being too rich for many ( core that is