I have the kitchenaid food grinder attachment for my mixer and have ground my own ground beef with good results. Page 4 of the kitchen aid manual indicates the following.
“Grinding Meat — For better mix and more tender results, grind beef twice. Best texture results from grinding very cold or partially frozen meat. Fatty meats should be ground only once.”
IMHO Chuck The best meat for hamburgers. I don’t mix it with anything else. Burgers always tase off to me when people add things to the mix. The only thing I use is salt and pepper as soon as it hits the grill.
When making hamburgers for a large group it takes way too long to grind my own so I just got to ShopRite the morning of the BBQ and ask them to to fresh grind 80/20.
I actually weigh 1/4lb of beef per patty being careful not to work the burger meat and use one of these Weston presses and Weston paper to form the burgers
https://www.amazon.com/dp/B000XB45DO/ref=cm_sw_r_cp_tai_8k05CbDG1QHQ8. I like this press because you can set the thickness of the burger just enough fo form the patty without squishing the grind.
I’m sure your burgers will turn out great!
Chris