Thanks,

Unfortunately it is just a simple sectoral horn. I've been lurking for multicells but found the price uncomfortable (>2k$ for 1505). AFAIK the Hiraga filter is tailored to the 15 cell horn with 288 driver. There is even an lift for HF in the curve, that should make things even worse. Currently the 288-8ks spit out way more HF than the 802s.

For now I think this harshness is not crossover related, but I didn't check out other caps or topology.