Niles Audio, control4 , crestron, sonus, and URC all have products that meet the OPs requirements. All will require an certified installer and be pricey. The programing can cost as much as the equipment FWIW
As far as I can tell only the Sonus would do what he wants, but not use his existing speaker system
The others are much more commercially orientated. The URC have a home system but it is part of total home control.
From what I have read only Sonus customers seem moderately happy. The issue seems to fall down with the compilers and there programming.
Unfortunately the OP has no clue as to the complexity and therefore the expense of what he is asking for.
Then you get into the range of the home router and that whole mess, which I have not even gone into.
These type of systems seem to attract people at first, so they start half baked, rapidly get out of their depth and realize what they want and tried to do is not practical.
I say what people really should do is decide which rooms it really is essential to have entertainment and then put a discrete independent system in those locations. Having audio everywhere is a ghastly prospect and worse than having silent spaces, which should be most.