Getting back to the room position of your speaker—-there is a phenomenon known as room modes where you have peaks and nulls of acoustic energy and these peaks and nulls can boosts in low-frequencies and distortion, as well as other problems in higher frequencies. Room modes typically have a more pronounced affect on lower frequencies however so without getting too scientific, move your speakers around and check to hear any changes in bass and midrange. You’ll have to go back and forth to your seating position.

As a rule of thumb, the closer to the walls your speakers are located the more “boundary reinforcement” you’ll get so that means you could potentially get more bass. Conversely the further away from the walls the less bass you’ll get. If possible avoid the corners of the room. Corner place results in a potentially very high level of boundary reinforcement.

Another rule of thumb is to apply the “golden triangle” approach, which basically means that you want to create an equidistant between your seating area and your speakers. A good example would be a pair of speakers placed eight feet apart and eight feet from the main listening seat. From there you can tweak toe-in/out and other basic positioning. If necessary use a tape measure or laser rule to ensure the distances are correct. This will also help to ensure “time and phase accuracy” that are essential to soundstage and image performance.

One last thing, if your receiver has an equalization option, try it out to see if it helps. These programs have improved dramatically over the years and they can help tame some frequency issues within your room.

Additionally if you have hard floors try throwing a rug on the floor to help deaden reflections. Also try putting some books in the room corners and if you have leather or other hard types of materials on you furniture throw some blankets and pillows on them to help with the absorption of sound. This may improve midrange and high frequency performance.