Stupid perfectionist that I was, I chose the Koss Pro4A back in the 70s instead of the lightweight Sennheiser foam model. The Sennheiser floated comfortably on the ear but did not seal out external sounds so well, allowing for a less pure sonic experience. I could not wear the Koss for long and did not use them much. Years later, I paid up for a pair of Stax electrostatics and kept them until the foam rotted away. Just walking around with Airpods these days.


