KOSS PRO4AA Studio Headset – 6.3mm + 3.5mm

KOSS PRO4AA Over-Ear Headphones – 6.5mm to 3.5mm Adapter

The legendary Koss Pro4AA headphones set the benchmark for professional, full-size studio sound. Originally introduced in 1970, they were the first dynamic headphones to deliver true full-frequency, high-fidelity performance — combining rich, accurate audio reproduction with exceptional noise isolation. Built to last and engineered for serious listeners, the Pro4AA remain a timeless choice for professionals and audiophiles alike.