On the topic of Mirage center channel speakers, I recently bought a used MC-si. This model from the 1990s has an unusual binding post setup, where an auxiliiary pair of binding posts is used to make some type of alteration to the frequncy response characteristics. (These extra posts are not for bi-wiring.)
The label on the back of the speaker says, "IMPORTANT. Do not connect these upper binding posts to your amplifier or receiver. For use, see 'Fine Tuning' in your owner's manual."
Of course I don't have a copy of the manual, and I can't find one online. Is there anyone here who has a copy of the MC-si manual and can post the text from the Fine Tuning section of the manual? Or maybe even post a PDF of the whole manual?