I recently got an e-mail from a reader suggesting that I review the classic Koss Pro4AA headphones. "They are the headphones everyone wanted when I was in high school in the mid-1970s," the reader wrote. I'm amazed that this product still is in production! Please consider a review of these classic stereophones from the golden age of stereo equipment. The Pro4AA retails for $99."

It sounded like a great idea, so I contacted Koss' public relations people. They let me borrow a pair of the Pro4AA, but as part of the deal, they insisted that I also try the much newer Pro4S. Here are my impressions of both.

The Pro4AA looks and feels like it was made in the 1970s, with its heavy-duty construction and thick coiled cord. The weight and shape made them a bit uncomfortable when I moved around, and they need a fair amount of power, meaning that they work best with stereo components, not portable devices.

The sound is neutral and very smooth. It lacks a little transparency, but the bass is solid, and the well-insulated earcups really isolate you from the outside world. With the lifetime warranty, good sound and heavy-duty construction, the Pro4AA is well worth the $99 price.

That said, I am very glad that I agreed to try the Pro4S. While I liked the Pro4AA, I think the new headphones are noticeably better and offer some significant modern advantages.

The Pro4S is lightweight and comfortable, and I found it very easy to get a good fit. The cord can be connected at either side. You also can daisy-chain multiple sets of the headphones together so more than one person can listen at the same time, which can be handy for watching movies on a tablet while traveling in a plane or car. They work perfectly with a stereo system or with portable electronics, though they do not have a mic or phone controls. They fold for easy portability and come with a carrying case.

The sound is lively, transparent, bold, natural and detailed, with accurate tone and no artificial emphasis at any part of the audible range. The Pro4S manages to sound exciting and accurate at the same time, which is very hard to pull off from a design standpoint because exciting usually means inaccurate and exaggerated, which quickly causes listener fatigue.

Selling for $149 on the Koss website with a lifetime warranty, the Pro4S has become my favorite headphone for under $200. I recommend it without reservation.

In doing research for this column, I signed up for the e-mail list at koss.com and immediately received a 15 percent discount on my first order. If you are interested in trying either of these headphones I suggest you sign up and see if you get the same offer. At the regular $149 price, they are a great buy. But with a 15 percent discount, the Pro4S is hard to beat.

Send questions to Don Lindich at donlindich@gmail.com. Get recommendations and read past columns at www.soundadviceblog.com.