Thanks for all the good advice!
It is nice to have the ability to build from scratch and all of the suggestions have been considered. Hidden bass traps, Conduit runs, separate circuits, pre-wiring for future theater.
I still get very confused with room size and modes, Effective and Interior dimensions. If i frame the actual room and if sound travels though the walls ( planning on iso clips- resilient channel and 2-3 layers of sheet rock) Do I base the dimensions off the foundation size or the actual framed room size?
What about ceiling? If the basement foundation is 9', and they use 10" floor joints does that mean i base the height off the bottom of the floor joist ( 9'ceiling), The basement floor to the 1st floor plywood ( 9'10") or the basement floor to surface of sheetrock?
Storage and functionality: this basement is pretty big and is one of the reasons for choosing this model. There will be a separate section just for hvac and utility, and another area for storage, recreation area etc.
Hopefully in the next couple months ill have some pictures of the foundation/house allowing me to give a better idea of space.
Thanks again
Erik