Here is another very favorable review which includes measurements of the Special Forty:
https://www.dynaudio.com/media/6622/dynaudio-s40-e.pdf
Note the on axis frequency response of +/- 1.5 db from 300 Hz up to 10k Hz! Very smooth indeed and when you listen that is what you hear as well.. a very balanced and refined speaker.
I bought a pair (grey birch) and have been breaking them in for a few weeks now. I am used to the classic Spendor sound (BC1, SP3/1P, SP1/2) and these Special Forty's have a beautiful midrange that makes me feel like I'm not missing anything. The Forty's are also very agile and fast especially in the bass notes. I am using Rogue Audio's RP5 preamp with Brimar 12AU7 tubes and the Rogue Stereo 100 amp for amplification. I also have a small REL sub I am using for the low end which is an excellent combo with the 40's. My listening room is approximately 13 X 15'.
I have also owned the Dynaudio Contour 1.3mkii bookshelf speakers in the past but sold those several years ago.
So far so good with the Forty's and a BIG thumbs up.
-Paul