Building new house need advice on a dedicated room

What's your budget. If you want the best, go with Riva. Don't ever use an installer or a regular contractor. Check out local brick and mortar audio stores for a referral, and do not make the mistake of using the store itself. Also, revise your forum query to include your zip code.

Be sure to place the entire foundation on seismic isolators prior to constructing the house. They will be very difficult to retrofit once the house is built.

How many times can the same question be asked?

In any case, Auralex.com has a whole section on it.

I would contact Art Noxon of Acoustic Sciences.

I'm also in the process of designing a dedicated listening room. Regardless of how you proceed I'd recommend getting the book Premium Home Theater by Earl Geddes so you're at least familiar with various design theories and approaches. Despite the name it's loaded with concepts and solutions that apply to a 2-channel listening room as well as HT. I bought a bunch of books on the topic and this one was by far the most useful and easiest to understand (at least for me). No matter which way you go you'll be glad you have an idea of how this should be done (and what shouldn't).

I spoke with some designers. They're expensive and I've heard results can be very hit or miss, and if it's a miss it's a really pricey one. After reading the Geddes book I feel confident enough (and I'm not a carpenter by any stretch) that I've decided to hire a contractor I know and trust to implement the construction techniques described in the book. In the end I'll save a lot of money and am fairly confident I'll have at least a very good sounding room (and if it sucks at least I know who to blame).

And I agree not to use a regular contractor. None of the ones I spoke to understand a thing about how to create a good sounding room. They all focus on how to sound "proof" so sound doesn't get out, but they have no idea how to design or build a room that sounds good on the inside. If you don't want to take my approach and/or don't know a good contractor I'd at least get a recommendation from a reputable high-end dealer for someone who specializes in this area who can give you references from past clients.

Best of luck and hope this helps.