Looks aside, the real reason why the PortaPros still remain classic (albeit underappreciated) is because of their fantastic sound quality. Just keep in mind that these came out decades before studio-quality sound-isolating headphones became available to the consumer market, so they definitely won't block out the majority of ambient noise. They also started to leak sound at the one-third mark on our iPod's volume bar, but we're not surprised given their open-ear design, just be sure not to crank it up too high around your neighbors. However, aside from that, we have very few complaints.
In our audio test, we compared the PortaPros with another set of foldable cans, Sennheiser's PX100 miniheadphones. We had good things to say about the PX100, but were ultimately unsatisfied with the lack of treble range. In contrast, the PortaPros simply blew us away with their range and ability to maintain quality at a high volume. We pumped several songs in a wide variety of genres through the headphones and each one produced a focused sound in the midrange with detailed resolution in the highs and surprisingly thick, head-shaking bass. Our MP3 of "Fatalist Palmistry" by Why? sounds much better with the PortaPros as well, clearly separating each instrument with equal balance while maintaining sonic realism. According to Koss, the sound output is handled by "neodymium iron boron rare earth magnet structures" that provide a 15-25,000Hz frequency range, which certainly sounds like random vendor jargon, but truth is that for the sub-$50 range, the Koss PortaPros are the headphones to beat.
If all that isn't enough to convince you to snatch up a pair, consider that Koss offers a "no questions asked" lifetime warranty on the PortaPros. If anything happens to them during normal use, Koss will send you a new pair for the cost of shipping ($6.00). Now, that's music to our ears.
