LX_EmergencyTo my ears, VERY similar sound. I'd say the KPH30i is a little less forward in the mids, has a touch less bass, very similar highs, but not quite as open sounding. It's a great sounding headphone, and it's $20. If you could somehow make them feel the same on a persons head a lot of people probably wouldn't even be able to tell the difference between the two. I think the PP is a bit more resolving, and KPH is a bit smoother. Kind of like an HD600 vs an HD650, but the difference isn't nearly as stark (it's really quite minimal). Comfort is excellent, cable/remote/mic is the same as the MD Porta Pro X. They aren't collapsible, and you don't get a storage bag. Also, I've only been able to find replacement earpads on the Koss site and they're $5 a pair (Black and Blue available) compared to 3 pairs of PP pads from Amazon for $5-$7. You get the same lifetime warranty, but as long as MD carries them it almost makes sense to grab a new pair if you do break them. I ordered one of each color.