Koss · Closed-back · 1970–late 1980s, and again since
Koss calls the Pro/4AA of 1970 the first dynamic headphone to deliver true full-range, high-fidelity sound with real noise isolation. It grew out of the Pro/4 of 1962, and Koss says about 50 Pro/4s were fitted to Air Force One's sound system in 1969. Koss retired the Pro/4AA in the late 1980s, then brought it back because people kept asking for it, so it's on sale new today. That's the main thing to know when buying used, since a listing can be a 1970s original or a pair made last year. The 1976 Pro/4AAA added the D-shaped Pneumalite cushion that shaped many later Koss designs. Koss still sells genuine cushions, which makes an old pair easy to refresh.
Before you plug in
The coiled cord is the usual weak point, and one owner of a 1970s pair traced its failure to a short in the cord. Old cushions harden, though genuine replacements are sold.
New to used headphones? How to check a used pair covers pads, cables, channel dropouts and fakes, and impedance and your amp explains what will drive it.
Buying guide
We'd buy the Pro/4AA titled works at $45 delivered from a 99.9% seller, or the boxed pair at $52 if you want the original packaging. There are at least 97 for sale and most ask $45–90 delivered, but Koss makes it again today, so ask when a pair was bought or for the label to know whether it's a 1970s original. It's 250 ohms and wants a hi-fi receiver's headphone jack or a headphone amp, since a phone won't give it enough voltage. Koss still sells genuine cushions, so worn ones are an easy fix, but the coiled cord is wired in and is the usual weak point, so ask for a note that both sides play with the cord flexed near the cup and the plug. Koss's lifetime warranty is written for the original purchaser only, so treat a used pair as uncovered, and skip the $490 pair from Spain and the $134 one from a 92.8% seller.
$15.89est. delivered
A beige Pro/4AA at $16 delivered on a no-bid auction, so it will climb. It isn't titled tested, so ask for a note that both sides play before you bid.
Koss PRO/4AA Headband Headphones - Beige
$44.72est. delivered
Titled works, at $45 delivered from a 99.9% seller, with the coiled cord and black cushions in the photo. The title says 3.5 mm but the photo shows a 1/4-inch plug, so ask which you'll get.
Koss Pro4AA Classic Over ear Stereo Professional Headphones 3.5mm Wired WORKS!
$51.97est. delivered
Titled with its box, a coiled 6 ft cord and a 1/4-inch plug, and the photo shows the vintage Pro/4AA box. At $52 delivered it's in the band, so the box comes at no real premium.
Vintage Koss PRO/4AA Over-Ear Closed-Back Stereo Headphones Coiled 6ft 1/4" Box
Delivered prices include shipping as eBay quoted it to a US address on Oct 14, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Snapshot
Checked . Some may have sold.
Delivered prices include shipping as eBay quoted it to a US address on Oct 14, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Used$15.89est. delivered
$8.37 + $7.52 shipping
Auction · no bids yet · ends in 4d 9h
Good buy
Auction, no bids yet, so the price will climb. Not titled tested.
Seller: the868113
100% positive
Used$44.72est. delivered
$34.99 + $9.73 shipping
Buy It Now$34.99
Good buy
Titled works. The title says 3.5 mm; the photo shows a 1/4-inch plug.
Seller: tetontreasures
99.9% positive
Used$51.97est. delivered
$44.45 + $7.52 shipping
Buy It Now$44.45
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled with box, coiled 6 ft cord, 1/4-inch plug. Box in the photo.
Seller: goated-finds
99.3% positive
Used$32.09est. delivered
$25.00 + $7.09 shipping
Buy It Now$25.00
Our take
Titled tested working. Seller at 98.7%.
Seller: kalibug1
98.7% positive
Used$48.45est. delivered
$42.00 + $6.45 shipping
Buy It Now$42.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled tested and working in both ears.
Seller: chrishes9
99.6% positive
Used$51.49est. delivered
$39.99 + $11.50 shipping
Buy It Now$39.99
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled 1970s, 1/4-inch plug. Not titled tested.
Seller: card_channel
100% positive
Used$133.64est. delivered
$117.89 + $15.75 shipping
Buy It Now$117.89
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Priced high
Seller at 92.8%. Titled with an extra cord, at about 2.6 times the median.
Seller: essexestateservices
92.8% positive
Used$490.40est. delivered
$353.58 + $136.82 shipping
Buy It Now$353.58
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Priced high
Ships from Spain with $137 shipping, seller at 97.7%. About 9.4 times the median.
Seller: technogold
97.7% positive
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