Brightness update

[brit]

"A perhaps crazy sounding tweak/test could be surrounding the tweeters of the 23 with a layer of foam. So simply cut out a hole the size of the diapfragm from a square piece of foam and stick it to the speaker. It's a bit like Wilson does, it'll focus the highs more towards the listener."

Re Antoine's suggestion above.

Russ Andrews actually markets, what he calls Focus Rings to achieve the same result - at a cost of course  . See here:  http://www.russandrews.com/focus-rings/.

I have not tried them myself, but they seem to be well reviewed. A relatively small outlay to try perhaps.
David