I cannot speak for the 804, but I owned the 704, 603S3 and the 684. First I owned the 603S3 years ago. I bough them based on the reviews (big mistake) and listening to them at the local dealer. Got them home and listeners fatigue set in after awhile. They seemed to exhibit strange harmonics that were irritating, and the treble was shrill and bright. So I got rid of those and a couple years later I thought I would give B&W another chance so I got a pair of 704's. After owning them for a brief time I concluded they were nothing more than dressed-up 603S3 in a nicer cabinet with the tweeter on top. To me they sounded about the same and exhibited all the traits that made me get rid of the 603S3. Then last year I picked up a pair of 684's locally. Personally they were the best out of the 3 models. They may have been a bit less resolving, but they seemed to have gotten rid of a lot of the irritating harmonics and bright treble. Even though I thought the 684's were better in this regard than the 603S3 and the 704, they still wore on me after while and I recently sold them locally. Not to say that I am done with B&W for good (maybe everything happens in 3's after all) but if I was ever going to try another B&W speaker it would have to be in the 800 series (no more 600 or 700 series for me). Good luck.
