Here is my review of FiiO RC-SE1, as a replacement cable for UE900 and W40, also works as a replacement cable for SE-series.
http://www.fiio.com.cn/products/index.aspx?ID=100000042227825&MenuID=105026014
Arrived in a small envelope with a clear panel view, its a straight forward packaging. I'm glad I didn't have to cut anything to remove these wires; it was easy to open and I will be able to re-use it in the future for storage. I know it probably makes sense to talk about the construction quality first, but I want to jump straight to a sound test
There is definitely a noticeable sound improvement. I spent at least an hour last night doing a/b comparison between stock braided cables (of both UE900 and W40), and going between different sound sources: my Note 2 by itself, with E18 connected, and new X5. I felt the soundstage opened up, and there was an improvement in bass and treble details. Treble definitely got more sparkle, especially noticeable with W40, and bass is more detailed and punchier (more noticeable with UE900). Also, the sound level improved because of a thicker wire thus lower impedance (lower voltage drop). With a sound level improvement, the dynamic range improved as well. In my opinion, FiiO's statement of "make the change with one tiny wire" definitely stands true!
The construction quality is tough, and will give you a piece of mind if your wire gets caught on something as you walking or moving around. Original braided UE wire always felt flimsy to me, while W40 was an improvement in terms of durability but RC-SE1 surpasses both of them. 3.5mm straight connector is solid, made out of metal, and you can unscrew the outer shell part, probably if you need to fix the wire. Coaxial connectors mate good with both UE900 and W40, although for W40 it was a bit tight fit because of the plastic housing of the connector and construction of this new Westone W-series. During the duration of my sound test, I didn't experience any dropouts. Also, there is a pre-shaped/curved clear shielding wire next to the connectors; it's not a memory wire you can bend. I actually prefer it because when I store my IEMs inside of the case, memory wires always get messed up and I have to re-shape it all over again. With this pre-shaped wire it retains the shape without a need for any adjustment. This cable is also tangle free, another big plus. There is also a chin slider - great for those who have problems with wires not staying put behind their ears. Considering it's a braided design, not too many manufactures include chin sliders with such wires, but I'm glad FiiO did.
There was also one included accessory, a shirt clip. At first I was a bit puzzled by it, but soon realized a purpose: microphonics
It wasn't as bad with UE900, perhaps due to more clearance with earbud connection, but it was worse with W40. The shape and placement of the connector on W40 made it more difficult for the cable attachment, although it worked fine. Perhaps, that was one of the reasons why microphonics effect was more pronounced with Westones. I can't comment on SE215 or SE535, since I don't have those at my disposal. This microphonics was very noticeable with music off. Once you start playing music, I didn't hear anything, or I should say - it was not noticeable enough to be disruptive. Since I'm using my W40 purely for listening pleasure at home, the benefit of sound improvement is significantly higher than microphonics effect
So, I can live with it. The only other comment I have, I wish there would be a version in all neutral-black color. I understand the original RC-SE1 was designed with SE-series in mind, thus a clear cable, but with more users of UE900 (blue color) and new W-series line (black and interchangeable faceplates), I think all black version of the cable would be highly welcome!!!
Overall, I think its a fantastic accessory if you can live with microphonics effect (when sound is off). That effect will also vary between different headphone brands. As I mentioned above, the improvement in sound is definitely enough to justify getting it, and for $30 (on amazon) its a bargain!
Here are the pictures.
