Tweaks when building a listening room?


I'm putting an addition to my house that will have a dedicated 2 channel room. It's fairly large @ 20'x 15' with 15' cathedral ceilings. I have 2 dedicated 20 amp plugs with PS Audio outlets. My question is there any tweaks as far as putting up the drywall or any other building ideas?
Thanks for your help,
Marc
brew
Some bass problems can be predicted from the room's dimensions; or, if you have not started the building process, the dimensions could be changed to those that minimize bass problems. Built-in bass traps designed by an acoustics engineer can be more effective and aesthetically more acceptable than after market units.
Thanks everyone for the input. I used every one's suggestions in some way or another. I'll give an update when the room is complete.
Thanks again,
Marc
Instead of 2 x 1/2 inch drywall, I suggest 2 x 5/8 inch. I also strongly suggest gluing the drywall to the studs & between the layers,in addition to screwing. Tape and mud the 1st layer before applying the second on an offset of course. The difference is not subtle and the cost is not prohibitive. Install soundproofing, tape and a trim piece along the gap where the drywall does not touch the floor. I would want a spare 20 amp line as well as normal 15 amp outlets per code.
I envy you-have fun.
If you need isolation of the sound from adjoining rooms, I suggest you read the information on the Green Glue web site.

http://www.greengluecompany.com/

Their testing indicates that two layers of drywall are essentially no better than one when trying to reduce sound transmission through a wall. The articles on this site are very informative.