Being as a couple of people are interested I'll add a couple of things.
No system is operating at it's potential in the average listening room. Good acoustics can have a profound effect on a system that you felt has been lacking somehow or actually in a multiple of ways. Once you hear your system set up in a room with good acoustics you really don't know how it sounds. Please remember the average room has peaks and dips of plus or minus 15db. That's alot
and can turn any system of any cost into crap. Good acoustics can make a system that's merely decent into a great sounding system. I know this for a fact.
The first thing you need to do is read. Go to realtraps.com and spend some time. The Acoustics circle here is an excellent place to ask questions. George's suggestion of the rat shack meter and 1/12 octave tones is a great place to start. You can get some graph paper for 1/3 octave measurements off of Rives audio site. In either case write time and date down.
Moving speakers including toe in and listening position is the first thing to do however. Moving in about 1" increments. Take your time! This is critical to start with the best position you can. The Tact can make this pretty much moot and if you have the money that's what I'd get. With the Behringer you have much less control but way more than you would normally.
Nearly every average room in existance will benefit from acoustic treatments. This includes bass traps. These can be made inexpensively or purchased ready made. In either case the improvement to the sound considering the money spent is excellent to amazing.
One more item that can be used is the Behringer DEQ 2496. This is a digital equalizer that can do room correction. It has dual 31 band graphic equalizers as well as parametric equalization for each channel. One can be purchased for 300 bucks with the ECM 8000 microphone and get excellent results. The device can be used in the digital domain and output to the dac of your choice.
With any of these dsp engines it takes time to learn to use properly. I am still learning after several months. I'd prefer a Tact but money is an issue and my sound is the best I've ever heard anywhere. The learning curve on even the little Behringer is steep. I've seen people sell them that I know couldn't have possibly learned how to use it properly yet. The Behringer is also good if you have little or no options for room treatments because your listening room is your living room or something and the wifey poo won't allow it
Another person here I know who recently did his room properly estimates any system of value of 1,500 or more should have good room acoustics. I believe this is a good cutoff point.
With good acoustics bass is amazing, imaging splendid and tonal accuracy much much closer to reality. The biggest problem area, the lows, ruin the midrange to a good degree. Being as all rooms have bass modes, assuming they have walls, it's an area that shouldn't be overlooked if possible. Now that I think of it I should come out with a line of furniture that works as room treatments and bass traps
