When I first took delivery of my QV I cranked up the bass setting. I have since figured out that doing this will trash the rest of the sound because the amplifier does not have enough power to drive more base, and also because the sub-woofer does not have its own dedicated amp. Furthermore, the sound coming from the woofers (not the sub-woofer, but the woofers) would sound very muddled and imprecise.
Listed below is a list of the tweaks and settings that I have made to the system, which has had a very positive impact on the sound quality:
1.) Turned off the surround sound option. I think it actually degrades the quality of the sound.
2.) I have not done it yet, but I will eventually replace the rear sub with a larger sub and a dedicated amp.
3.) I reluctantly set the bass setting to "0". The overall sound of the system is better when it is not trying to push so much bass.
4.) I discovered that the sound coming from the dash mounted tweeters is way to loud. This is not surprising considering they are firing directly into the glass, which then sends the sound directly into the driver and passengers ears. If I increased the tweeter setting to something greater than zero so that the overall sound would brighten a little, then the dash mounted tweeters would become even more annoying. I had some very thin round black chair glides that I bought from Home Depot with an adhesive back, and so I placed one of them in the very center of each tweeter. The idea was to reduce the sound coming from the teeters just a little bit, and it actually worked. I will probably look for a more permanent solution later on, but the chair glides actually do not look too bad. Before I installed them I stuck them to my forehead first to degrade the adhesive with body oil so that they will be very easy to remove.
5.) After I did #4 above I was able to increase the tweeter setting to +3, which brightened the overall sound of the system without making the dash mounted tweeters way too loud.
6.) I also found that the mid-range sound seemed to be way too loud, and I figured out that my left ear was getting a huge dose of sound from the middle speaker in the drivers door. I did not notice the same thing when I sat in the passenger seat, but it was very noticeable in the drivers seat. This excess sound from that one speaker in the drivers door also made it difficult to choose a balance from left to right in the car, and it made it difficult to find a good setting for the mid-range sound level. After more listening I finally figured out that the sound from the mid-range speaker was too loud because it was firing directly into the side of the steering column. The sound would essentially be concentrated in that space between the door and the steering column, and as a result the drivers left ear would hear way too much sound from that one speaker. I decided to reduce the sound from that speaker by covering up half of it with clear packing tape. I just stuck a piece of tape on half of the speaker, and then used a razor blade to cut a circular perimeter. The clear tape does not cover up the visual aspect of the speaker; it only reduces the sound. This turned out to the be perfect solution to reduce the excess sound coming from that speaker.
7.) After I solved the problem described in #6 above, I then determined that most optimal balance left to right balance was in the middle with equal sound on each side of the car. Before I covered up a portion of the mid-range speaker in the drivers door it would have been impossible to find a good setting for the balance.
8.) Solving the problem described in #6 also finally made it possible to find a proper setting for the fade from front to back. I think I settled on 2 (or maybe it was 3) clicks to the back of the car.
9.) And then after the balance and fade was set I increased the mid-range sound setting to +2. This setting had always sounded terrible until I solved the problem described in #6 above, but now the +2 setting sounds very good.
I am sure that other people will have different opinions regarding the proper adjustment of this system, but this is an accounting of what made the system sound better to my ears. After doing all of these adjustments I think the system sounds pretty darn good, and has eliminated any desire on my part to spend $4 or $5k on a major after market solution. The only thing I would like to do now is spend some money on a bigger sub-woofer with a dedicated amp.