Well, you don't need a contractor and I admire the DIY mentality the pervades in this country. I've been guilty of it dozens of times over the years. They can be fun and frustrating and in the end what I've learned in many cases is that I really didn't come out ahead, not all, but many. There is alot of good info out there. Now that I think about it www.auralex.com (I may have gotten a vowel wrong in there) has a nice article on building a listening room. Furthermore, they will even give free analysis of a room and recommend a set of acoustical treatments. However, alot of things can be deceptively complex. I'm not saying your not capable; the question is "how long a time frame are you willing to invest in educating yourself about the basics and then moving into the design phase?" By all means read up on it and educate yourself on it since it appears to be something you enjoy, and that's what life is about. But be cautious, and I guess many of us learn this the hard way once or twice, be open to what you may not know. Knowing the basics is one thing, being fluent in them is another. An acoustical engineer can easily get a crude estimate of a rooms characteristics just walking through based on what they know from schooling, and experience, its thier job. They spend eight hours a day doing it. The reason I'm going to such length over this is that its an entire room, this isn't the type of project that if it doesn't turn out less than ideal, can be sold, or eventually thrown away for a better one. Its there, now of course you'll still have an extra room to do something with and it may still be a nice listening room. Aside, you probably want it the best it can be. I'm guessing your stereo is pretty nice otherwise you wouldn't have decided that adding a dedicated listening room was the next logical step is getting the most performance for your money. Then again maybe their are more practical reasons like the stereo just isn't working in another room. You may want to just get on the phone with a couple of people who are qualified in designing listening rooms for recording studios and the like and just ask them "whether or not its a project that the average person could dedicate themselves learning about and do a good job in a realistic time frame (that is kind of vague) without any formal training?" Ask them how long it would take them to design a room and how much math is involved. They'll probably be pretty upfront about it to you. I just look at all these other diy project in the audio world, like loudspeakers and don't see how these people come out ahead. Yes, some of these serious hobbyist have pretty good mathmatical backgrounds, but designing a speaker well is incredibly complex and something I would never do. Fun projects can become stressful. If I were you I would spend my resources finding out where the best prices on materials are, talk to alot of acoustical engineers, read up on it, if for no other reason so that you can really talk with them at an in depth level, and even look into labor costs (just so you know your options), etc. Have a good grasp on all your options. The latter may be something that you were fine doing (the building part). By knowing your capabilities coupled with other's expertise you could come up with a really good listening room. Anyway, I'll end this lengthy reply. Good luck with whatever you do.
