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Koss Pro4AA Review: Premium Closed-Back Headphones

koss is an icon in the headphone industry, and deservedly so! I’ve loved basically every Koss product I’ve ever used, from the classic Porta Pro to the stunningly neutral KPH30i to the surprisingly comfy and cheap UR20.

Key Features

  • Closed-back circumaural design with titanium-coated drivers
  • Koss’s patented Dual Element and bass port design
  • Plush leatherette and memory foam ear pads
  • Oxygen-free copper voice coils for distortion-free sound
  • Extended 15Hz-25kHz frequency response

Weighing just 11.8 oz, the Pro4AA feature clever weight distribution for all-day wearing comfort.

Sound Quality

The Pro4AA deliver warm, smooth bass, lush midrange, and open, airy treble in a beautifully balanced sound. From intimate jazz to thunderous hip-hop, they bring out the emotion in music.

The soundstage is spacious for closed-back headphones, with precise imaging that reveals micro-details. Highly resolving, they uncover nuances missed by less capable headphones.


Constructed from premium materials like stainless steel and plush leatherette, the Pro4AA exude luxury. The sturdy build promises years of intensive use.

The soft memory foam ear pads provide exceptional comfort for long listening sessions. The ear cups fold flat for travel and storage.

Customer review

“I have been in the radio business for 40 years and came off the air 5 years ago. In all those years this is my go-to set of headphones. I was offered a job at a local radio station and my first thought was to get a new pair of headphones and the Koss Pro 4 AA was my first choice. They still sound great. This is not a pair of phones that you can wear for hours at a time but for a few minutes on the air that are the best.”

“The product materials and speakers and really good for the price. However, these headphones will not be very comfortable or sound really until you get some fixes. There’s multiple ear cushion replacement that give much-needed extra foam and room for your ears (stock pads press a plastic mesh right onto your ear). Not the easiest to change out but not dissambly required. Use an adjustable equalizer if you’re not happy with the stock sound (mids and highs are great but bass is lacking) as the speakers have the capacity for good sound. With aftermarket pads the weight distribution of the headphones is great, but make sure you’re into having heavier headphones.”

“These phones are amazing. Yea they kinda squeeze your head and are a little heavy, but why let that hold you back? They block most noise and sound fantastic, like hearing things I never heard before in songs I’ve listened to dozens of times. Get some better pads like I did and they will be your best friend. I use AirPods and wish I had my work phones whenever I’m away from my desk, seriously they sound like crap compared to these.”

Customer questions & answers

Q: Does any company make a hard shell case for the Pro 4AA?

A: I don’t think so.

Q: Can anyone identify a hard shell case that will fit these cans? Thanks very much! CD

A: I made my own.

Q: Are these old K-6 stereo headphones worth anything?

A: Well not sure if I can help you out on these, I had a pair of these back in the 70’s when they were considered by many to by the standard , they were a studio quality headphones with a full frequency range( first to have that). At the time I paid if I reminder correctly close to $200.00 dollars for them. I bought them again somewhat out of nostalgia, I don’t think they are they same quality they were back in the 70’s sound wise, they certainly are built with the same ruggedness, they are heavy headphone by today’s standards.

Q: found an older pair in a thrift store for 2 bucks should i pick them up?

A: They’re worth the 2 bucks.

Q: Where are these made?

A: Milwaukee

With their lush sonic beauty, premium aesthetics, and incredible comfort, the Koss Pro4AA represent one of the finest closed-back headphones available. For discerning listeners seeking ultimate quality, they are highly recommended.


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