The 2X10s would be overkill. I would focus your money on db-3 acoustical barrier and celotex fiberboard. These together will push the STC over 100. Building the detached walls will help the STC significantly so you may only need one or the other. If you decide to only use one, I would also use 5/8" Sheetrock.
After your done if you want to improve the sound quality within the room I would recommend my acoustic panels:
I am not sure you have enough field experience with the statements you have made on this thread...
In my decade of field work ( assembly design and field testing have I never seen 100 STC ....maybe only reading 4k and up but never based on the way STC testing is done...
I would like for you to post proof of an assembly ASTM E90-09 or ASTM E90-02 test results for the material you recommended. Even our Mass loaded vinyl can not reach those values standing alone.
To the thread writer
Squeaky floor boards need to either be re screwed from above or subfloor blocking to pull the subfloor back down.
As for increased STC you will need to increase the mass to at least 8-10 lbs per sqft. minimum based on standard 5/8" sheet rock that would be about 4 layers ...
This falls under " Mass Law" where you must double the weight or density in order to achieve 5 db loss over what is heard through a standard interior wall.
If you want to build the "Tomb" then you are looking for upwards of 15-20 lbs per sqft.
" You can not talk through 6" of concrete but if I impact or low bass you can"