Koss introduced us to the Porta Pro in 1984, long before I ever start embracing this hobby. It was one of the first headphones developed specifically portable use. Who knew it would be around 30 years later, relatively unchanged, and still popular as ever? Competition has come and gone within that time, but the Sennheiser PX 100 has been a popular portable in this market and, in my opinion, is the Porta Pro's closest and strongest competitor. In this comparison, I'll be reviewing the Koss Porta Pro and Sennheiser PX 100-II.
Let's start by talk about the traits both of these cans share. They are both small, lightweight, portable headphones that can collapse to make them easy to store and transport. Both are of an open-back design and, therefore, will leak sound both and and out of them. This is good if you want to be more aware of your surrounding and want a more airy sound, but is also bad if you don't feel like disturbing anyone around you who are relatively close. Both are extremely efficient and can be driven from portable devices with no problem. You don't have to worry about additional amping to get optimal sound out of either of them. Both are inexpensive with the Porta Pro retailing for $49.99 USD and the PX 100-II retailing for $69.99 USD. Both are also offered in variants with an in-line mic and iDevice controls for a little extra ($79.99 for the Porta Pro KTC, $89.99 USD for the PX 100IIi).
The Porta Pro is mostly plastic with a sliding adjustable metal band. The cable is a dual-entry cable that is thin and can tangle easily. It terminates with a flexible 45 degree 3.5mm jack that is going to help when it's connected to a device that you can throw in your pocket. Although the overall construction is strong, the materials feel cheap. Have no fear because, and this is a big one, Koss gives you a lifetime warranty with the Porta Pro. They break and you go get yourself a new pair... forever.
The PX 100-II is mostly plastic as well and has a metal and plastic band with traditional indented adjustments on the side. Pictures of this headphone are deceiving to me as they appear to be cheap and fragile, but that is not the case here. There is a good weight to them and the materials are very very nice. The cable is of good quality as well and is only a single-entry which makes cable management easier. Unfortunately, it terminates to a straight and rigid 3.5mm jack which may not play as well with a device in your pocket. The PX 100-II clearly has better build quality and construction over the Porta Pro, but only comes with a two-year warranty.
Comfort is a very personal thing and, therefore, I can only speak to my experience with the headphones. Both are very comfortable on my head. They're light enough that I can't even tell I'm wearing them after a while which is nice during long waits in the airport or long flights.
The band on the Porta Pro has a tendency to catch and pull on your hair. There are also "comfortZone" adjustments you can make on the side that range from Light to Firm. I have never seen a need for those side adjustments. The clamping force is tight, but not to the point of bothersome. What is annoying is the sliding adjustment band needs to be continuously adjusted if you are taking the Porta Pro on and off your head. The ear pads themselves are standard foam that are very soft to the touch.
The PX 100-II has less problems to deal with in terms of fit and comfort and that is mostly due to the more traditional indented adjustments on the side. Clamping force isn't as much as it is on the Porta Pro, but never feels unsecure. There are also no pressure points created around my head. The ear pads are slightly stiffer to the touch than the ones found on the Porta Pro, but the difference can't be felt when worn. For me, the PX 100-II takes a slight edge in overall comfort over the Porta Pro.
Rubber hits the road time. Sound is a very personal preference and everyone hears things differently, so I will attempt and explain the differences between the two without adding too much color. The Porta Pro and PX 100-II have very distinct and separate sonics. Both produce a very high quality sound, but their signatures are significantly different.
The Porta Pro is closer to neutral and more aggressive than the warmer PX 100-II. I would even consider it slightly cool. The bass has some weight to it, but I wouldn't consider it extended or impactful. Mids seem balanced. The treble is extended, but somewhat splashy and inaccurate. There is a decent soundstage that's airy with good separation of instruments.
Conversely, the PX 100-II is much warmer, darker, and laid back. Bass is more extended and more impactful. The mids here are also very balanced. The treble is rolled off, but decently accurate. This is a far more intimate experience over the Porta Pro. Less airy and less separation, but still relatively detailed.
So you have a decision to make based on preference and the type of music you listen to. If you want a more aggressive sound, the Porta Pro can deliver that. Want those warm and laid back sonics, the PX 100-II is your can. I have a feeling most people will prefer the Sennheiser sound over the Koss as it work better in environments where you can't control the outside noise levels. For me, I prefer the more aggressive sound of the Porta Pro. Whatever you pick one thing is for sure. Both of these headphones hit well above their weight class. Both sound much better than sub-$100 cans they are. I would go as far as to say the Porta Pro and PX 100-II have been the most impressive (not best, obviously, but impressive) headphones I've ever heard. However you choose, you just won't believe prices this low will get you sound this good.
If I had to pick just one of these headphones to throw in my bag, I'd be very sad. Both have their own strengths and weaknesses, but let's just say you held a gun to my head and said "Pick!" I think my answer would still be, "Must I?!" They are both that enjoyable. Now let's say you just got to the end of your rope and started pulling the hammer back while pushing the barrel into my temple. If it ever got to that point, for me, it always goes back to using the right tool for the job. That specific job we're talking about here is portability and convenience while traveling. Although I prefer the sound of the Porta Pro, I would probably pick the Sennheiser PX 100-II due to the slight advantages in comfort, cable management, adjustment, and construction. No matter what you pick, though, you win.