Following the original Koss SP/3 in 1958, the improved SP/3X was released in 1960. Listeners of the era were experiencing stereo headphones for their first time. People were won over by this revolution in personal listening. It was around this same time that Koss coined the phrase "Hearing is Believing". Below John C. Koss remembers the SP/3X, and the challenge of introducing the world to stereophones.  "Back then, if you handed somebody a set of headphones- they were very big and unusual looking- people didn’t really know what they were. So, the headphone was nothing when you saw it, you had to hear it, and then it was like your first ride in a car or something like that." John C. Koss with the SP/3X in the early 1960's. The SP/3X is listed in a Koss catalog from 1964. The T-2 Headphone Adaptor Plate. These were included with every SP/3X, and served as headphone outlets in a time before headphone jacks. "At that time there were no jacks on any amplifiers. We developed a little adaptor you'd just tie onto the speaker outlets and you were in business." "Because it was so new, people would invite the whole neighborhood to come hear it. They wanted to run their own hi-fi show. That's kind of the way it worked all along. You had to hear it to believe it." Tony Bennett with the SP/3X in 1962. "We found out if you're trying to advertise something that people have no concept of - a headphone on a page wasn’t going to work. We needed to tell people to go and try it, that they wouldn’t believe it. When we did that, it was a challenge, that's how we got people to try them and understand what they were."