Koss Pro4S review: Lightweight studio monitor headphones for engineers, producers and attentive audiophiles

The Good The Koss Pro4S headphones have a closed-back design that attenuates outside noise while keeping sound leaks at bay, while the memory foam ear cups keep them comfortably seated on your head. They come with a detachable cable that plugs into jacks on either side of the cups, and Koss includes a ballistic nylon carrying case, in addition to its generous lifetime warranty.

The Bad Their naturally even register may weaken the "edge" of some artificially-produced songs. The headphones come with a coiled cable, but it's missing a microphone and an in-line remote control for changing tracks and adjusting volume through a smartphone.

The Bottom Line Although we regret that Koss doesn't include a remote on the cable, the Pro4S is an excellent studio monitor headphone that audiophiles will appreciate for its neutral sound design, forward-thinking features and generous warranty that guarantees no-question replacements for life.

8.0 Overall
  • Design 8
  • Features 8
  • Sound 8
  • Value 8

The Pro4S over-ears ($149 in the US; available in the UK and Australia for about £130 and AU$190) are part of a new trio of headphones recently announced by Koss, but while the SP330 and SP530 take aim at the average music-loving consumer, the Pro4S are studio monitor headphones designed to be used in a recording studio by audio engineers, producers, and anyone else at the source concerned with a clean sound without aural additives.

Koss is up against tough competition in this marketplace since many of the current best-selling "professional" headphone monitors like the Sennheiser HD280 and the Sony MDR-7506 have remained in the winner's circle for more than a decade, but the Pro4S hopes to deliver the audiophile's fantasy of an accurate, noise-attenuating headphone that can be used for both studio monitoring and everyday listening.


Headphones built for studio professionals are concerned a lot more with sound design and all-day comfort rather than modern notions of aesthetic appeal like bright colors and flashy materials, which could explain why some of the industry standards have remain aesthetically unchanged (and kind of ugly) since the 1990s.

Sarah Tew/CNET

The Pro4S, on the other hand, puts a modern spin on some of those classic headphones without sacrificing necessary comforts like a ear cups wrapped in memory foam, a wide, generously padded headband, and a supremely lightweight chassis that weighs just under seven ounces.

I tested these headphones for a week and they're exceedingly more comfortable than the bulky Sennheiser HD280s, to the point where they become almost unnoticeable while they're on.

Sarah Tew/CNET

Instead of the usual circular padding we see on most over-ear headphones, the Pro4S features D-shaped aluminum ear pads that are offset at an obtuse angle relative to the headband so they sit a little further back on your head, which actually feels more secure and resistant to accidental movement while you're listening.

Music professionals will be thankful to see that the Pro 4S gives the option to connect the included coiled cable to either the left or right side. Additionally, the empty jack can still output audio so anyone else with their own headphones can also plug into the listening party without bringing around one of those annoying little headphone splitters.

Sarah Tew/CNET

The ear cups swivel 180 degrees to allow the listener to monitor with an open ear, and both ear piece sections fold up flat against the headband for compact travel in the ballistic nylon carrying case included with the headphones.

You'll also find a smaller pouch with a quarter-inch adapter inside so you can plug the headphones into a home receiver or mixing board, but I was disappointed to see that Koss doesn't include another cable with an in-line microphone and music player to navigate tracks and adjust volume on the fly.

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