Back when the JBL L-100 was king of the showroom, I discovered the Electro-Voice Interface "A". In terms of performance, it was considerably better than the L-100, with a low end that was solid down to the mid-30s and IMO a considerably smoother overall response. Unfortunately, the woofer and PR had rot-prone foam surrounds and its little (SEAS?) cone tweeters were as delicate AF -- but to my younger self's ears it was the best "bookshelf"-sized speaker available at the time. Despite requiring its (very modestly speced, unlike the Bose 901's) equalizer, it was also considerably less profligate of amp power than the ARs, KLHs, and Advents of that era. It also might have been the first widely-available speaker designed according the now-standard T/S math, which most folks don't know includes provision for the use of electronic EQ.