It is fine to mix these two proteins together.
-You'd be better off taking the ON Whey post workout and take it later in the day. ON Whey is a much better protein than muscle milk. Please don't waist your money. Right now, it's really not economical to run 2 proteins, I'd invest in Pro Complex over the muscle milk.
*You could take the Pro Complex inbetween meals and ON Whey strictly post.

-sorry if I got carried away, that's what I'd do above. Much better options than muscle milk.

sorry, what I mean to say was that it's not economical to run 2 proteins but if you were going to i'd invest in Pro Complex...sorry for any confusion.

Whey Protein for after workouts and if you're looking for something prior to bed, I would look towards cassein protein. You want cassein because it is a slow digesting protein and most of us should be sleeping a good 8 hours a night which means a minimum of 8 hours between meals. If you're looking for a good one, ON makes a good Cassein.
As far as Muscle Milk, the only Muscle Milk I ever use is the Ready to drink version and I use simply as a meal replacement if I'm on the run and don't have time for a meal.
The problem is it is pretty pricey per serving and many would say not worth the money. IMO if you're looking for a meal replacement, I would look towards Cytosports Cytogainer instead of this and just cut the serving in half.

If i were you i wouldnt take it before bed because of all the fat and i think there is some carbs to. You would be best to take it in the morning because you have time to work off the fat. You could take this as an mrp to. but like these other guys here said take casein before bed.

beast - bro fats are better for you before bed then they are in the morning, they slow digestion which is what you want before bed, if you have alot of fat in the morning then ur metabolism slows down - not good. Carbs are the ones you dont want at night as they block GH :-)

Thnx for the info. man but like shouldnt optimum add some fat to their casein then? because i see that ON casein has only one gram of fat.

I agree totally with Kubitzky10- Listen to him, he KNOWS what he's talking about. And btw, there are better things than muscle milk. - Look up my review on it.