B&W 802D1 - How can I tame the brightness?

I’m gonna get trashed for this, but damn, it works!  
The 802’s are equipped to biwire.  Single wire them instead, using the woofer input, the lower pair.  Connect a jumper between the upper binding post ground (minus, or black) and the lower binding post ground.  Instead of using a jumper between the two positive terminals, use a 2 ohm, 10 watt resistor. This will lower the output of the midrange and tweeter drivers by a small amount.  Too much?  Use a smaller value resistor, they’re available in increments of ohms.  I suggest a high quality resistor such as those by Dale, Caddock, or Vishay if you like the effect.  Resistors are comparatively cheap and using them won’t harm anything and is easily reversible and amenable to experimentation.  Just so you all know, Wilson offers the option of switching external resistors to tailor the high frequencies to taste as does Magnepan. In fact, any speaker that offers high frequency tailoring uses some variation of this method.

I fought a brightness battle with my B&W 801 Matrix speakers. I then fought a similar battle with my Wilson Sasha 2s. I now love my Rockports. Save yourself the battles. Sell them and find a sound you love.

+1 find a sound that you love.  A speaker that will draw you into the music, a joyful place like no other.  Move on, this one ain't it.  

You haven't mentioned any room treatments. For sure I would treat the first and secondary reflection points.  I've used GIK art panels and further added Owens-Corning insulation to this with excellent results.  My hearing is sensitive to high frequencies anyhow and this made a big difference for me.  This will improve the sonics in just about any room and no matter if you change speakers, it will improve your sound.  Also agree with the others regarding toeing the speakers straight out and not in.  

You might look at using Marantz gear with the B&W. Marantz lean toward the warm side and can help tame those speakers