None of those choices will work. The internal crossover for the RS 8 Kappa is 80Hz. With any of those choices, you’ll be rolling off the mids/highs way too high.
http://www.infinity-classics.de/technik/manuals/Kappa_8_technical_sheet.pdf
http://www.infinity-classics.de/technik/manuals/Kappa_8_technical_sheet.pdf