If you have a separate zone for the theater and is on while watching you may be able to hear it. If it on with the other zone, you could shut the opening so you would not hear it.
Consider a hot water recirculating pump and well insulated hot water pipes. With that tankless, it would run when water is not running to have hot water at faucets.
A high performance home should have staggered stud exterior walls for added insulation and less outside noise entering.
Of course double pane windows. Check out air tight drywall approach/method.
High R value in ceiling and under floor if not on a slab on grade. And, even on slab, consider foam insulation under the slab, again a good R value.
Theater: make sure you have ethernet to equipment cabinet; HDMI run to projector if one is used. Don't use ceiling speakers for your 3 front speakers and surrounds, only for Atmos setup; Two locations for possible subwoofers with power and RCA cable.; 12/14ga speaker wire, not expensive audiophile cables
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If a projector is a possibility, a way to darken the room totally.
Vent equipment space to cool amps.
Don't have seating against back wall.
Ethernet cable in other areas besides a study. Sure wi-fi is good but ....