Yes indeed there are studies enough around to explain you what the differences can be between a bulk in house brand and a premium or super premium dog food.
I have read them all, I spoke to many vets including professors at Universities and they all say the same. If you want the best for your dog...read the labels at the bag, see how the balance is between prote?ns/fat, is the starch product based on corn or a much better alternative rice (brown rice is still better), are the minerals balanced (phosphor, calcium, sulfate, etc...) and are the added vitamins artificial or coming from a natural source and the most important, what is the meaning of the "flesh" or "fish" in the kibble.
For me personally, is there isn't enough written explanation on the bag on how its composed, I simply do not buy it.
Add that up and a premium food should have its flesh or fish content coming from real flesh and fish and not of the bones, the starch should not be corn but rice, the vitamins and vitamin E to preserve should come from natural sources and the balance of the minerals should be good and preferably the kibble should have some additional herbes thrown in such as parsley, garlic, moon seed sometimes etc...
This food does indeed come not cheap but it guarantees you a dog who has a shinny coat, a good working digestive system, a good immune working system (my dogs don't even get flees and ticks) and a happy dog with tons of energy.
I see a lot of dogs here that have absolutely no energy at all, young dogs and I can only say from my experience that that comes from the lack of a descent dog food. Bulk in house brands are so heavy for a dog to digest that they don't have any energy left to do something else anymore.
The alternative is switching to raw (Barfen), its a proven system, needs a lot of calculation per dog a few times in his life to assemble the correct diet but then your off (Barfen diet does not work per day but uses a calculated diet that is spread over 5 to 6 weeks to ensure that the dog gets everything he needs in that period)
Downside of this diet is that for here its impossible to get enough variety in the diet, essential additives are not available or I haven't found them yet and you have to have a big freezer to put all that stuff in.
Eitherway, for now I am giving the dogs and the pups the best available dry dog food here available and maybe in the future I will switch again for all dogs to raw, I do it now occasionally for one or two dogs for various reasons.