yellowferrit:
Sorry, but I'm going to muddy the water for you.
Don't know what your budget is but I recently auditioned the 684's against 683's to go with Cyrus 8 series equipment I was buying. Yes, the 684's have more body than the 685's but, to my mind (and ears), the 683's were substantially better again. I bought them and haven't for one second regretted it. They are £200 more expensive but fully justify the additional expense.
Again, I think room space has to be the deciding factor here. Plus whether the rest of the kit is up to the task of driving the bigger speakers properly. I wouldn't dream of just adding bigger speakers with twice the number of drive units without at least adding a power amp to cope. And to do the 683's justice you wouldn't really get away with just slapping any old cheap tack on there. Personally, I think running a pair of 3 way 684's (never mind 683's!) off of a 70 WPC wich cost only half as much as the speakers is a bit optimistic and not exactly an ideal match.
This is why I was considering and suggested a subwoofer (for myself) first as not only are you getting the extra power needed built in but also the flexibility to tune the bass to suit.
You just have to let room size be the first consideration, THEN the maximum you want to spend. Simply just filling a room with bigger speakers just because they're within budget is stupid.
My room is borderline to get away with either 685/4 so I went for the smaller/cheaper 685 leaving the option open to fill the room out a little more with a sub if I decided it was needed (plus I went for wall mounting at first). Yes, with stands and everything it works out the same price as a pair of 683's but I'm getting 200 extra, quality watts of power and I haven't got two towers of veneered MDF dominating the room (lets face it the 600 series still isn't exactly classy looking, is it?).
Since room dimensions don't grow with speaker budget and if you will insist on having B&W (which I can fully relate to
) wouldn't it make more sense to be looking at some stand mounters from the CM range if you wanted to spend more than 685 money in one shot? Being brutaly honest though, I'd only even consider this route if I was intending to upgrade the other kit later on.