Koss Corp. Europe

10 - 25000 Hz, 3.5 mm, 95dB, 250Ω This full-size professional quality stereophone has long been the headphone of choice for broadcast and recording professionals whose careers demand reliable equipment and superior performance. As the first dynamic stereophone to deliver true full frequency, high-fidelity performance, the PRO4AA set the standard when it was introduced in its original form in 1970. In the late 1980s after long service, it was retired and replaced by a newer model. Customers clamored for its return, and by 1988 it was brought back by popular demand. Since then, though we've incorporated performance-enhancing technology and updated its style, the essence of the PRO4AA remains unchanged and it continues to set the standard for performance and reliability today.

The PRO4AA Titanium features dynamic elements for an exceptionally wide frequency response from 10-25,000 Hz. A 2 mil. titanium coating on its diaphragms increases the rigidity of the element, minimizing mechanical distortion and ensuring exceedingly accurate sound reproduction. One-inch (25.4 mm) diameter oxygen-free copper voice coils improve signal transmission and conduction for cleaner, clearer sound. For times when every note must be captured and no sound allowed to leak through, closed PneumaliteTM cushions form a positive, comfortable seal around the ears, maximizing bass frequencies and isolating the listener from ambient noise.

Designed for frequent use over extended periods, the PRO4AA's durable steel and rubber headband is generously padded. Adjustable slide bars ensure a snug fit, also critical for hearing every note and keeping unwanted sounds out. The heavy-duty, single-entry eight-foot coiled cord affords ample flexibility of movement. A 3.5 mm (1/8") plug and a 6.3 mm (1/4") screw-on type adapter, both with gold-flashing, are included.