I had a chance to hear some MB Quart Q's in my friends T-bird and here are some of my impressions. These are very accurate speakers, almost to a fault. They will reveal nuances in your music you didnt ever hear before, but they are very unforgiving on poor quality audio (ie MP3, radio, etc...)
I didnt find them to be too bright with the highs, just very accurate. You could easily take care of the problem with a good equalizer.