Not for Portable Use

In the '70's, I was a DJ at the college radio station and afterward had a show for 5 years in Jacksonville. I remember the Koss Pro 4aas well. Back then, they were the set by which all others were measured. Built like a rock, they had a smooth range from the deepest bass to the highest treble. They were closed as opposed to open air design. They were heavy, gave you a headache if you wore them too long and made your ears sweat. . . and it was all worth it for the sound they produced.

I just bought the modern incarnation of them last week and 30 years later I find myself saying the same things about them.

In my opinion, these are colorless in sound. They will reproduce exactly what is on the source material. As such, they will sound either incredible or terrible depending upon what you throw at them. As you might expect from a closed-ear design, they excel at reproducing deep bass. It is solid. The midrange is smooth, and faithfully renders vocal without any extras. A good test for high frequencies is how they handle violins. If they sound like they are made of steel as opposed to rosin scraping a bow, they are not good. The Koss Pro 4's produce a "silky" sound that is extremely natural.

It is unlikely you will suffer from listener fatigue when using these. Although they list for $99, they compare in sound and quality with headphone costing much, much more.

They are very efficient, so you shouldn't need an auxiliary headphone amp for them. But, as with any set of headphones, start with the volume relatively low and very gradually move it up. Because the sound is so clean, you may find yourself cranking these up beyond safe level.

Of course, there is a price for this type of sound quality. The most obvious is that this type of design will isolate you from the rest of the world. A good thing if you have noisy neighbors, it is late at night, or you don't mind missing phone calls or people ringing the doorbell.

I would say they would be a hazard if you connected them to a portable CD or MP3 player and went jogging, but I would be surprised if you were to do that. As stated before, they are have a high build quality and in this case it translates to them being much heavier than you may be used to wearing. For some people, the sheer weight may make them unwearable. However, if you can get passed that, these are one of the best sounding headphones on the market. At the price you can get them for over the Internet, they are a bargain to boot.

They come with no documentation, other than a registration card that has the most straightforward warranty: a lifetime guarantee.