Thinking of a new room

Hello All,
I am planning of moving my audio room from the main floor to the finished basement. The current room dimensions are 13.5'X12.5'X9'. In the basement, the new room would be 12'X19'X7'. In this room, the 3 walls are solid concrete and have foam insulation on them. They are finished walls. The fourth wall needs to be built from 2X4s and might need insulation of some kind. I would like to get suggestions on how this new wall should be built so that it makes the room soundproof, if possible, and also to make sure that it does not sound bad. This is because the wall parallel to the new wall would be concrete wall and I feel that the new wall might need some extra "something done" - not sure what. Also the door will be on this wall. Any recommendation on what kind of door?
In general what about the old Vs new room dimensions? Do you think the low ceiling will mess the sound? I do plan to use the GIK traps that I have in my existing room.
I will build it of 2x4 pack insulation between the studs and double Sheetrock then carpet the wall use a thick underlay.

You will not hear anything outside. Let us know how it goes
I would insulate with R 15 comfort batt made by Roxul. Would also attach resilient channel for the drywall and would use a drywall call Quietrock its equivalent to about 5 layers of normal drywall. Best of luck