I haven't decided if you're nuts or you deserve a medal :^).
I posted the question pretty late PST and you still responded same
night in a later time zone. Anyway, I'm not sure I understand the
last comment about generating a shelving response before augmentation.
I'm assuming that what we are attempting to do is produce a filter
that has a mirror response to the published freq. response curves
for the horns. To me, that means I need flat up to ~12K, then
+6dB/octave (or more) on up. Am I missing something?

Thx, Chris