Thanks selmeralto.
Yes, the unit I’m referring to is the Eton B100 XHP (
https://www.eton-gmbh.com/en/product...uct/b-100-xhp/).
I believe it is a high pass crossover (filter) ahead of the b100w separates or b100c/cn coaxials, so passing just the non sub frequencies to them as a whole. Then there is another crossover that sits in the cable between the b100w woofer and tweeter and I assume is in the coaxials as well.
I couldn’t find the specs on the B100 XHP, but Eton’s own amp high pass filter is 120 Hz for the b100w /c /cn , so I suspect it is around that and they recommend to use the XHP in passive systems with exactly these speakers.
I would have thought the stock HK amp would have active DSP / filters for this, but now it doesn’t seem so. I’ve tried to EQ with the tone controls but the subwoofer bass overwhelms any bass that might be coming out of the Etons. So it’s just boomy down low without any attack and completely missing any upper bass.
I’ll probably pick up a couple of these XHPs and install them to see what happens, but the cheapest I see them is $50 a piece which is very expensive for what they are.