B&W 801 D4's with the Technics su-r1000 WOW !!

[Boomerang]

Wanted to start a new topic, but am not allowed to yet....
So I will post it here.
In the last week, I did some measurements at my 801D4.
Glad to obtain a frequency respons quite similar to the results of HifiNews in their review.
What wonders me is why /how BW changed the output of the woofers between 90 en 400 Hz, (minus 2db) also compared to the 800D3. (As HifiNews also mentioned)
I measured the output of the low pass and there could be a kind of explanation.
The transfer curve is not what I expected for a 18db Butterworth filter.
So maybe it isn’t Butterworth?
Coil and capacitor values also point away from a straight butterwort design.
There is a +2 dB ripple at 80 hz, maybe a measuring faillure, maybe the answer?
Repeated this measurement several times, always the same result.
Btw: all of this measuring started because I wanted to try Bi amping, leaving the original cross over for mid/high (absolute top components here) but making low pass analog active, still third order at 420hz.
But surely, that 2db ripple at 80 hz will be gone then, so what will happen with the sound quality....
Exchanged MC312 for 2 x Michi M8 a month ago.
MC312 can not cope with Michi regarding low frequency power and control, but I think the Mcintosh was a little more refined in the mids/high.
So bi amping with both of them, could maybe make me even a little more happy.
Will keep you guys posted.
Should there be someone here who also did some measurements and/or knows more about the crossover layout of the 801D4, glad to hear your comments!