Mixing a low carb food with California Natural?

I started out feeding my 2 Blue Buffalo Wilderness (dry). They were having digestive issues and their vet said the food may be too rich for them. She recommend Royal Canin. I was not thrilled with the ingredients in that, so I searched for a food that wasn't totally grain-free, but didn't have a bunch of stuff like corn in it.  I decided on California Natural, happy that it is so simple and the only grain is rice.  However, it's still a little more carb-heavy than I'd like (32%).  I read that a lot of people here feed a mix of dry foods, so I am considering mixing a very low carb food with the CN to cut the carb level down a little.  I am considering Nature's Variety Instinct or Wysong Epigen 90.  I'm not considering EVO b/c I'm trying to avoid fish and the ash/mineral content seems really high!  Leaning toward Epigen--the ash is only 5.6% which is pretty low considering it has 90% meat, and seems to have less fruits and veggies and stuff they don't really need.  BTW, they do not eat only dry--they also eat wet and raw (not in same meal as dry).  What do you think? Any others i should consider?

I don't know much about dry foods....Matt's digestive issues are almost always triggered by dry. But I really like California Natural and find it sits well in Matt's sensitive tummy. Hollistic Blend  sent me a sample of their grain-free dry food, and Matt took well to that one, it was pretty good i think for carbs? here's the website.....www.HollisticBlend.com.....you can find out for yourself.

 I feed Matt a combination of wet and dry, and the dry i feed is Wholesome blend easy to digest., paired with california natural, weruva, wellness, or hollistic select canned food as my top picks

you can look up wholesome blend at www.nutreco-pet.ca(though i'm not so sure about the20% crude fat myself)

I'm considering Innova Prime--it doesn't have fish and is almost as high in protein as Evo. But I haven't looked into the ash/mineral content. Take a look and let us know!

ETA: but I do think that Epigen 90 is probably the best if the price isn't a problem.

Willowy, The Innova Prime has ash- 8.99%, magnesium- .12%, and phosphorous 1.5%.  These are lower than EVO, but still seem high.  And I realized after I posted that the N.V.Instincts have fish in them, but the Instinct L.I.D. doesn't, so if I went with N.V., that'd be the one.  I spoke with Wysong rep. today, and she said the Epigen 90 has ash- 5.5%, magnesium-. 09%, and phosphorus- .65%. These seem very reasonable for a food with so much meat/protein, almost in line with urinary tract formulas.  I think I'm gonna go with the Epigen.