The Koss Pro4S is a no-frills, budget priced over-ear headphone designed to be used in the studio, but are just as versatile to worn on the streets. The $149 full-size headphones fold flat for easy travel, and come with a single telephone cord style cable that can be plugged into either earcup. The downer is there are no track/volume controls or microphone on the cable, but you could swap in a third-party headphone controller. You just have to buy it.
The headphones look decent, fit well on my head, and had good adjustability options. The earcups are “D” shaped as opposed to most over-ear headphones which are either round or oval shaped. The headphones are well constructed with a combination of plastic, fabric, foam and metal parts, but the headband leans towards the cheap side. Oddly, they are flagged with a California Proposition 65 Warning, but I was never told exactly why. Meanwhile, the Pro4S are lightweight and pretty comfortable. I was able to wear them for a couple hours before any discomfort.
I listened to them on a plane, walking in the city, and at home. They don’t do a great job of blocking outside city noise or plane engine hum. Also, wind can strangely be heard through them on windy days. Of course, they’ll sound best in a quiet studio or around the house. However, the Pro4S are pretty durable. I accidentally dropped them a few times, and threw them into various different bags. They survived without a dent and only had a little discoloration around the Koss logo after two months of testing.
Ultimately, if Pro4s match your style do they sound good enough to buy? I am torn with mixed emotions, mainly because they do some things well and other things I wish were better. Overall, they sound flat and neutral with no particular area where they outperformed, unless you’re looking for neutral. On the other hand, there are no glaring problems either — just areas I wish were better. But my reference point may be a bit skewed from the norm, because I’ve tested much pricier audiophile headphones recently. So perhaps my criticism is a bit unfair, since I didn’t have another similar model on-hand to compare.
To my ears, clarity in the treble region is the biggest weakness. Although, bass is tight, but never very deep. Mid-bass has a nice kick, and it is never in your face. But, if you like your music with extra bass, the Pro4s are probably not the headphone for you. Instead, Koss recommends their SP540 model, which keeps the same drivers, but has the bass tuned way up. I didn’t have a chance to test that model, but I’d point you to try them or perhaps the competition with Audio-Technica’s ATH-M50x.
Regardless of my perspective, I do think anyone buying headphones for the first time would find the Pro4S a major upgrade. There is no doubt they sound better than cheap earbuds and fashion earphones sold everywhere. I also think they are a great alternative to Beats, which seems to be the question I get asked most often. Plus, these Koss headphones are about the half the price. So definitely put the Pro4S on your consideration list.