Originally Posted by niic
Great read! I'm really curious now to the history of headphones after the Koss SP3s!
Here's a brief history of KOSS.
After the SP/3, Koss went on to designing the PRO line.
They started with the PRO/4, which still used the basic paper cone drivers of the SP/3. It wasn't anything special.
After that, KOSS made the PRO/4A, which was the transfer into mylar drivers. This is when KOSS' headphones really started to gain their reputation. The 4A was much more detailed and natural sounding than its predecessor, and was pretty popular.
After that, they made the famous PRO/4AA, which has been a favorite among their customers for a very, very long time. The 4AA uses liquid-filled earpads and a foam-padded headband, increasing the comfort of the 4A nearly tenfold. The drivers had also been tweaked to give it more treble and more bass. To this day the 4AA remains the most loved KOSS headphone ever made.
A couple years later KOSS took it a step further, and designed the PRO/4AAA. This headphone is basically a 4AA on steroids. Better build, better fit, and better sound. It was the best dynamic headphone in the world at the time of its release; the only headphones that could outdo it were electrostats. It never saw the amount of fame that its predecessor did, but it is certainly one of the best headphones KOSS ever made; easily comparable to many modern headphones in the <$500 price range.
Unfortunately, KOSS headphones became so immensely popular that the company really seemed to stop trying. Once the 80's hit KOSS completely changed and re-released all of their headphones, all of which used significantly cheaper materials and a newly redesigned driver. All of the "Plus" versions of KOSS headphones use the same series 3 driver, with a thinner membrane, weaker magnet, and smaller voice coil. The detail is nonexistent and the sound is tinny and distant. One of the worst sounding headphones I've ever heard.
They seem to be getting out of that habit a bit with headphones like the ESP/950, but they really just don't care about sound as much anymore.
Edited by takato14 - 4/16/13 at 12:41pm