What sound quality? Well, very good. The sound is sweet, not aggressive even music that packs a punch. The midrange and treble its detailed well, even if we do not reach the surgical precision of Q-Jays, definitely if there were magical fragility. The lower midrange is clean, as are the bass that are quite detailed, but without falling into the caricature of boom boom. I find generally balanced, but of course, do not expect to go down to low frequency of small headphones that can not reproduce. In its price range, the S4 are the best headphones I've owned.
Why then give only three stars? Klipsch has a big flaw in my eyes: the tips. First, only three sizes are provided. Compared to the cost of these accessories, this limitation is totally incomprehensible. This could be accessory if earphones fit in well with the ears. But this is not the case with. I do not think individual ear canals because until then, with any in-ear headphones I've owned, it was enough to let the tips of medium size and all was well. With the S4, I tried three bits and none is satisfactory.
First, the implementation is difficult because the headphones are curved. This does not necessarily see in the pictures, but between the end headphones and the main body of the object, there is an angle. If the aesthetic effect is certain choice hampers implementation, requires fumbling for pressing the headset is not enough to push the end caps, and embarrassing, it even provides a relative discomfort. It is also difficult to find the right depth between a tip enough down into the ear, or too depressed and becoming painful. Then, take the headphones wrong when traveling and insulation is often lost on the road. When stopped, I finally found a good position to take advantage of good bass, but walked, I can sometimes lose the insulation on one side. I do not know what the user panel which was used to test ergonomics for tips, but it makes you wonder if some family members of Mr. Spock have not crept into the lot. I finally put the maximum size of nozzles which are those that allow me to limit as much damage. So beware if you are used to size L with other brands because you may not find any mouthpiece that will fit you well with these Klipsch.
In summary, these headphones give you complete satisfaction if the tips fit your ears. Therefore difficult to know until you try them. When we see the importance of insulation for in-ear headphones is a significant uncertainty factor.