Pros: superb build quality, low-mid frequencies, scene rendering.
Cons: the prominence of the high frequencies, sometimes confused. Not for noisy environment use. Shallow ear insertion.
I have to say, as introduction: I'm not an audiophile, just an "enhanced" user with more than 20 years of analogic and digital listen. I use mainly portable devices, some Fii amplifier, and I listen pop-rock-ethnic (50%) classic (20%) and jazz (30%) mainly lossless. And finally my english, it's not "mother tongue style", sorry for this.
This product (on amazon, 60 euros) has an elegant and robust big box where, in addition to the IEMs you find a little semi-rigid box for transport, and 4 sets of eartips, one of them is foam made. Overall I have an idea of strong build quality. The IEMs looks pretty nice with the metal dark shield and the red/black cable flat, Y shaped with the microphone for phone usage in the left branch, and a slightly heavy junction in the Y. The shape of the wire warrants is actually tangle free. The plug is metallic, gold plated and L shaped. All seems to be robust and build with care. After 3 months of heavy daily use and travels nothing is changed/broken.
These IEMs are easy to fit because of the asymmetric shape of the canal for the insertion, but I couldn’t find the tips to ensure to me the best insertion and isolation (could depends on my ears, but it’s the first time I have problems like this), because the insertion is shallow, so I used a third part eartips with slightly more success. With the proprietary tips the acoustic isolation is lightly below average and, by the way, the quality of the bass in the noise environment is a bit compromised. The flat and rigid shape of the cable can give microphonics problems when you walk, because at the junction of the Y the cable has a weight that tend to fluctuate. So it’s better to avoid to keep portable device in the pants… use the jacket and block the cable.
Personally I don’t like the bass-head in the iems (such as the monster turbine or the senn’s CX300), but I understand that in some noisy environment (street, metro) their use can balance the tonal shape broken by the noise in the bass side. In this sense the Philips fidelio S1 have a more balanced response actually not bass-head. So they are not suggested for whom likes the over-bass, and also for frequenters of very noisy environment (this is due also to the non-perfect acoustic isolation). On the other side I don’t find these IEMs to be light or weak in the bass side. At the opposite is the high to be more prominent.
Talking about the sound. These IEMs have a very large frequency extension, significantly above others IEMs I have managed. They are overall balanced with a certain predominance of the highs tone that sometimes (depending on the quality of the records) can be harsh and tiring.
the Lows are present, punch and detailed, refined and well controlled (U2, all the recent registrations). Never overflowing and well extended (Lumb, my angel Gabriel). The bass transition towards the mids gently and with the same control and detail richness (Maria Gadu). Smooth and liquid, with a good balance, the mids are at the same level of lows with no predominance or lacking, and no coloring. Actually well done, the best part of the IEMs, above average for the cathegory.
The highs are more in evidence respect to the rest of the gamma. Ofthen clean and detailed, but the evidence can be abrasive (Can’t stop, Red hot chili peppers). In particular I note the low rate MP3, and the old analogic recordings to be particularly affected to be harsh, sometimes generating little sibilance and affecting the perception of the details. For those who are listeners of 80’s recordings (low dynamic range and highs pumped up: Prefab sprout, from Langley park to Memphis) the Fidelio S1 are actually problematic. More in general I noticed that the quality of the recording is a problem and the iems are little tolerant. In particular the female voices can result slightly sibilant and unnatural, and all the registration have a smoothnessless near 12kHz, where I suppose is the peak (slightly uncontrolled) of the high frequencies.
More tolerance and more balanced when listen high quality lossless Jazz (Paolo Fresu quartet), where the guitars and trumpet are well rendered and separated (due also to the enhanced reproduction of the harmonics) and the contrabass centered and detailed in the scene. To the v-shape lovers could be suggested to use a +2dB near 100Hz to obtain this effect (techno, rap).
The detail its abundant and the scene is wide and airy. Instrumental separation is above average.
In conclusion the fidelio S1 are a good pair of IEMs where the low-mids area is well rendered and detailed. These are not bass-head but definitely balanced, with the exception of the highs that sometimes render harsh and occasionally sibling.
Since these are not bass prominent, and since they have a below average isolation, I don’t suggest the use in a very noisy environment. They are efficient (slightly below the average) but the use of an amp suggest me the improvement of the dynamic bass range. The forwarded reproduction of the high enhances the defects of the low quality recordings (low sampled mp3 and old recordings), so I do not recommend to listen low mp3 recordings.