I recently took a trip to Europe and one of the things on my "to-do" list before I left was find a decent pair of headphones that would travel well, since I didn't want to drag my bulky studio headphones along. So with over 26 hours of flying in 10 days, I wanted a pair that could block out a lot of noise and put out good sound quality for the money. I stumbled upon the Klipsch brand and the S4i headphones, and I'm glad I did. These have been without a doubt the best in-ear headphones I've ever owned.
The first and most important thing is sound quality. The highs are great(when listening to certain songs, I heard hi-hats and tambourines that i had previously not heard), mid range is excellent and the low mids are impressive. However, what sold me the most was the bass response. The bass is there, without being too powerful, but when I wanted some brainthumping bass, I turned the EQ on my iPod to "Bass Booster", and I was blown away. These little headphones pack a punch, that's for sure. Bass that can't be replicated by my Infinity 6 x 8's in my car was played with ease, and with little distortion. The only issue I had was slight distortion when playing songs that had both a deep bass line and a punchy kick("Forgot about Dre" by Dr. Dre) but other than that everything was darn good. I wanted to listen to a wide variety of music for this review, and everything sounded great through these, from AC/DC to Jay-Z,Miles Davis, Cake, Outkast,Common, Arcade Fire,and Neutral Milk Hotel, it all sounded flawless, and many tracks I felt I was listening to for the first time since I heard hi-hats, guitar riffs and bass lines that I hadn't heard before.
The sound isolation is also nice, having an 8 hour trip from Houston, TX to London, England, I didn't have to listen to the crying babies with popping ears or most of the engine noise(there was a slight drone, but turning up the tunes solved that problem).
The headphones we're quite comfortable as well, although I think Klipsch could have designed them a little better if the 180 degree insertion method wouldn't have to be used every time. I only had trouble with them when I had fallen asleep for about an hour on one side of my head, and upon pulling out the earphone my ear canal stung for a while, but other than that they we're quite comfortable.
These seem like they're pretty well put together, although I think for this price the wire could be a bit thicker, I'm not entirely sure how long the wires will last, but I can't see any problems in the near future as long as they are taken care of well.
I don't have an iPhone so I wasn't able to do much calling, but did successfully make a few calls from my iPod Touch using VoIP Stunt and both my call quality and my voice carried through well. The earphones block so much sound, however, that I could not hear myself speak very well and was almost yelling into the microphone (the person I called appreciated this none whatsoever).
So as you can see there are a lot of benefits to buying a pair of these. Sound quality is great (especially on Miles Davis' "In A Silent Way"), they're reasonably comfortable, work well as far as making calls (again I didn't try on an actual iPhone) and should hold together if taken care of.
The few gripes I had were nitpicks at best. If they would seal well without having to turn them 180 degrees that would be great. They could include a few more sizes of ear tips as well, but foam tips are cheap and can solve this problem. Other than that these are great and I would certainly recommend them for travel and everyday use, just mind the thin wire!