Without having used a Breville 800, I dont think you can quite compare them to a commercial machine. Its bit like jumping into a truck after driving a Daewoo - you cant quite compare methods of operation even though similar principles are involved.
Firstly, what sort of coffee are you using? If it is from a supermarket shelf, it may well be stale. Go to a good roaster and buy a bag of beans that was roasted no more than a month ago.
How does the coffee taste? If it tastes good, then you dont have to worry.
If it tastes weak and sour then it may be under-extracted and you should try a finer grind. But first things first, make sure you are using good quality freshly roasted and freshly ground coffee.