Ill start by saying the entire 6xx Series line from B&W.
I had a pair of B&W DM602 S3 bookshelf monitors (ones with the 7" midbass) and I was and still am stunned at how they sound. My longtime friend, who posts here under the name "yettitheman" has then now and he feels the same way about them as I do.
I can't expect everyone to share my taste in speakers or sound, but I'm surprised that the 600 series is the most disappointing thing you've heard. What conditions did you listen to them? What was the source material?
The most disappointing speakers I've owned were Boston Acoustics CR57 bookshelf speakers. What surprised me about them was they sounded decent enough for a speaker their size, and the midbass driver was robust. The problem I ran into was the incredibly weak 3/4" kotex tweeter. I would have thought a tweeter with an extruded aluminum heatsink would have excellent thermal capability, but even when powered by modest equipment the tweeter became damaged. Apparently even a hint of clipping just eats those tweeters up, which makes be think the heatsink was an afterthought because of the driver's poor ability to handle any level of thermal problems.
So either they became damaged, or the tweeters just resonated at certain frequencies regardless, in any case, I was very disappointed given the overall build quality of those speakers.
