A couple of thoughts on this subject, as in my last house, I spent great efforts, money and time building as neutral a room as possible. The aim was soundproofing, as well as being dead - my version of a chamber.
Anyway, on the studs - this is for a non load bearing wall - especially if you follow the link and use 2x2 studs. I did not see that mentioned in the article, but may have missed it.
The essence of all of these treatments is to eliminate sound waves penetrating, or going through the materials. All materials also have a resonance, or frequency at which they will resonate or vibrate. By building with multiple types of materials, the sound waves will not make the traverse completely through a wall/celing/floor, as something in the composition will stop the wave at the frequency.
While it is difficult to tame this, it is not entirely impossible. I used a combination of most of these methods, and as painstaking as it was, the rest of the house rarely had to endure anything noisy.
I would be careful with the load balancing of the HVAC, as it was correctly mentioned that it is a tuned system - or should be to operate efficiently.
