The earphones were burned in for 20 hours which should be more than enough for balanced armature in-ears. During the first 10 hours we did not notice any change to the sound signature. The earphones were tested with the Cowon D2, HifiMAN HM-801, and iPhone 4. The Westone 4s are a bit harder to drive than the old Westone 3s but any decent DAP or PMP will be able to power them close to their limits.
The new Westone 4s are radically different sounding compared to the Westone 3s in a number of areas. The first thing you notice with the new 4s is that the sibilance issues that the 3s had with the normal thickness single flange tip is now completely gone. With the Westone 3s you had to use either Shure Olives or a triple flange tip in order to get rid of that issue.
Back when the Westone 3s hit the market we were surprised by their sound stage capabilities. And now a year later with the Westone 4s you get the same kind of wow effect as with the 3s back in the day. The sound stage is bigger and slightly more coherent on the Westone 4s in comparison to the Westone 3s. With the Westone 3s you were quite close to the instruments with the Westone 4s it sounds as though you are positioned just a couple of rows further back.
Sound stage wise these are ahead of the pack and completely demolish the Sennheiser IE8s in that respect. All of the positioning clues are left intact with the 4s and that really completes the listening experience. Listening to The Persuasions sing a cappella really showcases the vastly improved midrange of the Westone 4s over the previous design.
Detail wise the midrange seems much better, every little quality that gives a voice its feel is portrayed beautifully. The midrange is quite cold in comparison to the Westone 3s, and is almost as dry as that of the Head-Direct RE0s. Coming from the somewhat hot midrange of the JH AUDIO JH16Pros to the Westone 4s really highlights their cold and totally linear midrange.
Tonality wise the Westone 4s bring a little more midrange to the table compared to the Westone 3s, which is great because one of the only noteworthy cons with the 3s was the somewhat recessed midrange.
In terms of bass they have enough for the average listener, they are not extremely bass heavy so bassheads might want to stay clear. The bass is on the other hand very snappy and extends really low. It is more linear than the bass you get from a set of Westone 3s, and it seems like it interferes less with the midrange.
Another small thing that is just a notch better with the Westone 4s is the way they handle percussive sounds. They have just a little more punch and control which makes them sound more natural.
Compared to the recently reviewed Jerry Harvey Audio JH16Pros (our review here JH AUDIO JH16Pros). The Westone 4s sound more midcentric and more analytical. The force of the JH16Pros is their detail, bass, and musicality and while I would not call the Westone 4s strictly analytical their flatter frequency response and less dominant bass makes them more ordinary to listen to.
Treble wise the JH16Pros bring forth more details and a touch more intensity. The thing that sets the two apart is mostly the way they handle the treble and the amount of detail they retrieve with the JH16Pros having an edge. Bass wise the Westone 4s also turn up short in comparison, but for the price they do a good job keeping up with the much more expensive JH16Pros. The midrange of the Westone 4 sounds quite neutral and cold coming from the JH16Pros.
Since the exterior design of the Westone 4s is an exact copy of the Westone 3s the ergonomics are very good with the 4s as well, if not a little better because you can get optimum sound quality with all the tips included.