 The IRS (Infinity Reference System) was an ultra-high end system, selling at US$65,000 in the 1980s.It consisted of 76 EMIT tweeters, 24 EMIM midrange drivers, and twelve 12-inch polypropylene woofers in four towers.The Reference, and later Kappa series, were discontinued when Nudell sold Infinity to Harman Kardon.