Tweaks when building a listening room?

Double-rock the drywall and use the very best sound insulation you can afford between the studs. There's a very dense specialized batting for sound, or blown-in is excellent as well. If you plan on running any systems in other rooms you may consider running some wires before the walls are buttoned up. Cat-5, speaker wire, and a set of coaxial wires would all be useful in running an extension system. I also did two dedicated 20 amp circuits and kind of wish I'd done a third.

Good luck!

I know its not cheap, but have you considered using the spray foam insulation ?

We did the whole house ( outside walls / attic ) last year with this to save money and it also did a good job of I guess you could say soundproofing the house.

If interested, contact me and I can send a link and it will show a video of the work that was done.

I recently finished a dedicated 2 channel room and used double 1/2 inch drywall and all walls were double insulated before the drywall went up. I too brought in two 20 amp circuits and two 15 amp circuits for power.

The best tweaks you'll make will be after the room is finished using room acoustic panels.