The Kappa Series was the next series above the Reference Series, but was below the IRS series (Infinity Reference Standard). No question the IRS Omega is the better speaker. It was one of the last classic Infinity speakers & used the later and much better High Energy Emim & High Energy Emit drivers in a transmission line arrangement (similar to IRS Epsilon), a 12" Watkins dual voice coil bass driver, Watkins midbass coupler & a rear-firing Emit-R tweeter. Add bass and tweeter attenuation & you have a pretty cool package.
Also note: the Kappa speakers you mentioned use old Polydome K midrange diaphragms which deteriorate over time and become dried, yellowed & eventually crack. Harmon have long since ran out of NOS replacements, thus you have to take your chances on Ebay etc to source replacements. Another interesting bit of trivia, Harmon later used the IRS-Omegas to voice their Revel Gem speakers.
