The Koss Pro4AA has been around for ages, and when you listen you'll know why. Koss got the sound right the first time. And while contemporary headphones have more features and are lighter and more comfortable, they're nowhere as ruggedly built as the Pro4AA. This headphone will shrug off more than a few mishaps that would shatter to pieces a lot of 2013 designs.
So if you're rough on headphones, you might want to pick up a pair. And since they're covered by a lifetime warranty, Koss will keep repairing or replacing them forever. The warranty is for the original owner only, and you pay shipping fees to and from Koss.
The headphone weighs a hefty 19 ounces -- that's more than double the weight of the average full-size headphone sold today. The Pro4AA has changed little over the years, but the early versions' liquid-filled ear cushions were prone to leak, so Koss now uses more conventional pads. It's a closed-back design, and does a good job blocking external noise.
On Beck's "Odelay" album the Pro4AA's bass was solid, with good resolution of detail and dynamics. Switching over to the $199 Audio Technica ATH M50 headphones -- one of my prime references for closed-back, full-size headphones in this price class -- the Pro4AA's sound is weightier and deeper. The M50 has more midrange detail, but the Pro4AA is more laid-back, so when you turn it up loud it sounds less harsh. Amy Winehouse's "Live at the BBC" CD demonstrated the Pro4AA's luscious midrange quality; her vocal talents sounded more naturally reproduced than what I was getting from the M50. That one is no slouch -- it's more open sounding, and it's a higher-resolution headphone. But the Pro4AA sweetens the sound of marginal MP3s. Its added warmth and fullness make MP3s go down easy.
The Koss Pro4AA's 10-foot-long, nondetachable coiled cable, 6.3mm plug, and high impedance (250 ohm) tag them as mostly home-oriented headphones. Even so, I popped on a 6.3mm to 3.5mm adaptor plug and tried the Pro4AA with my iPod Classic and the sound was more than decent. True, the Classic couldn't play the Pro4AA all that loud, but it was loud enough for me. At home I used the Pro4AA with my NAD C 316BEE integrated stereo amplifier.
Koss offers a wide range of contemporary designs, and I'll cover some of them in the future. But I'm happy they're still making the Pro4AA. Great sound never gets old -- Amazon's user reviews awarded the Pro4AA with more than 120 four- and five-star raves, and just 12 one- and two-star pans, demonstrating the 43-year-old product still has strong appeal for today's headphone buyers.