When I got the 8331 I had a brief chance to compare them with the 8330. I think I have written a detailed description of that here before, but in short, the 8331 sound is sooooo effortless in near field listening. The first reaction was meh... sounds about the same, but then I noticed I didnt need to tweak the volume as much as I used to and it was ’easier’ to listen to music for longer periods of time. The pro studio people seem to talk about ear/listening fatigue and I guess this is the case. They also seem to claim that the coaxial design in the 83x1 series helps in this area a lot.