Did you purchase the D2415K?

Looking at the wiring and manual it looks like only one woofer reaches 1.3kHz, and that would be the middle one, right under the horn (white wire vs green ones).
This is also hinted by the position of the listening axis in the manual, right between that woofer and the horn:
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Now, the SCL2 being a 2.5 way (as per its spec sheet), that particular woofer does not have a 225Hz high-pass filter.
Having the three woofers playing in the < 225Hz range gives a 3.5dB SPL capacity boost compared to only two, but at the cost of more IMD in the 225HZ-1.3kHz range.
Makes me wonder why they did not use other woofers more suited for LF (and cheaper with more conventional cones and motors) in the < 225Hz range, letting the pricey synthesis 8 woofer concentrate on the > 225Hz range.


... or maybe my guessing on the SCL2 crossover topology is completely off
(that 6 ohm / 92dB/1W/1m spec sure looks suspicious...)
Could the upper and lower woofers (green wires) be the ones that go up to 1.3 kHz, and the middle one (white wire) be the help woofer??
That would match the sensitivity rating, and even match the listening axis advice in the manual, but I find it hard to believe...