As much as I'd love to discuss eggs, where I feel I have a much higher degree of expertise, please allow me to redirect...
Let's say I build a structure like this:
Two normal 16" on center 2x4 stud walls with 1/2" drywall about 5" out from the two concrete walls.  Two walls with staggered studs built on a common 2x6 base, each with drywall on both sides.  A 2x4 framed ceiling with drywall attached to the new walls but completely de-coupled from the main frame of the house.  Three electrical boxes, one solid core door.  Concrete floor with carpet.
What can I do to this structure to improve upon its sound-proofing qualities? Someone mentioned "high density insulation" ...like what?  Any particular product?  Would adding more drywall help, to a degree where its worthwhile?  Would some other product help?  What would be the best way to ventilate such a room?
Thanks again to all posters.  I guess I'm just getting frustrated, kind of feeling a vibe of "this is practically impossible, just give up now."  Maybe I should.  I can take up wind-surfing or growing my own tea or something.  But really, is it not possible to take a significant bite out of the noise output with a room like described above?