I use electric filters in my speaker systems because they do not perform well without them. I do not feel that a filter degrades the sound any, so I guess one could be used on a horn if required. I am still new to horns and have not spnet much time building, testing, or listening to one. For me, a SS amp allows an easy implementation of a filter because the efficiency of the speaker is not critical, there is plenty of power. I am not sure I know how else to answer your questions.

Martin