I'm doing a shoot-out of the Porta Pro KTC with my Original Porta Pro, the Triple-Fi 10 Vi, and the Etymotic ER-4P, and so far, my results are as follows:
The two Porta Pro models sound exactly the same (which should be the case being that the only "feature" added was the inline remote/mic). The soundstage is somewhat narrow and the treble is veiled. The bass is the definite strong point with the Porta Pro. For a $30-$40 headphone, it's a remains an excellent value, and if you pair it with a portable amp, it'll flesh out the mid range a bit more. I can't say how it'll sound with most amps, but it shines with my Simpl A1. In my earlier post, I also mentioned how the Porta Pro/A1 combo almost approached the sound of the Triple-Fi 10 Vi. Well, that'll teach me to not to be too hasty. After more extended listening, that is not quite the case. The Triple-Fi bass is deeper, louder and just better quality, and the treble and imaging is better.
I know this is a review about the Porta-Pro, but I must say a few words about the ER-4P: In my opinion, it is the best headphone in this bunch. It doesn't play as loud as the Triple-Fi 10 Vi or the Porta Pro, and it gets smoked as far as amount of bass, but this headphone DOES EVERYTHING ELSE BETTER THAN EITHER OF THE OTHER PHONES. It is airy, the midrange is better, and although there isn't as much quantity when it comes to the bass, the bass it produces is very high quality. And this is with a variety of music ranging from Jazz, Pop, R&B and Latin. This of course is my opinion, and I love each one of these phones, but it seems like I'm always coming back to the Etys. They are THAT good!
As far as my opinion regarding the Porta Pro KTC, my advice is if you don't need the remote/mic, get the original Porta Pro, and save yourself some cash. I don't think it's worth the extra $40 just to get that. The extra money would be better spent on either better headphones or an amp.