The ER4 has a very specific sound that is very polarizing. Comments on ER4’s sound range from bright, sibilant, thin, lifeless, baseless to clear, accurate, and detailed. However, after having the ER4 for a long time, I will describe the ER4’s sound as articulate, pristine, quick, and precise, though definitely a little on the thin side in the sub-bass area. There are so many things that the ER4 does really well, and it all adds up to a sense that you are listening to the music using a precision instrument. You get a feeling that you are hearing all the clarity and details that you have never heard in your music before, as if the music is injected straight into your brain without the obstruction of air. Each sound and instrument is very distinct and separate from each other, and you can listen to and focus to each instrument and sound in the music easily. There is off course a bad side to this, as I will mention later.
There are several factors that contribute to the ER4’s unique sound character. One of it is that the ER4 has very quiet background behind the sound. The black canvas is painted with vivid sound images with great transient attack and sharpness. The sounds attack and disappear swiftly, never dragging in the background for too long. Smearing from note to note and from sound to sound is minimal, and different sound images are rarely mushed together, giving the ER4 a good instrument separation and a sense of quickness to its sound. However, though the ER4 has good instrument separation, its soundstage is definitely on the small side even for IEMs. The soundscape plays in a sphere in the middle of your head, and the instruments are close to each other.
ER4’s mids and treble are both outstanding. Treble, especially with the ER4S is very clear, detailed and well extended, definitely one of the best in its price range. The mid is also clear and slightly on the warm side, with a bit more emphasis on the upper mid. You can hear the sound of the guitar plucked, lips smacking, and the fine details in the recording. The bass though, is a love or hate. On one hand, it has a surprising textural detail, able to reveal some texture behind drum hits, while on the other hand, it is almost too tight and lacks ample impact. The bass also rolls off a bit early, making is less suitable for some music, notably pop, dance, or RnB. The good side is that the bass presentation doesn’t stand in the way of other parts of the frequency range.
For all the good qualities, and clear, detailed presentation that the ER4 has, it is definitely not neutral. The sound is simply a bit thin sometimes, especially in the ER4S setting, and less full-bodied than real life sound. The emphasis on treble and upper mids, with relatively less mid warmth means that the ER4 is giving a raspy quality to voices more than what exists in the recording. The ultra fast attack and short decay is almost too fast.
Talking about detail, the ER4 also tends to focus in a specific area of the frequency response. It is detailed in a sense that it really pushes out the details that reside in the upper mid and treble area to the front, while other areas of the frequency response are a bit in the background. The thud of drums and airy instruments including strings, cymbals are pushed to the front in a crystalline but a bit lean presentation. Some instruments like bass, cello, and percussive have just enough body but the decay is very short. A lot of people try to make the ER4 sounds more liquid with amplifiers, source, and cables pairing, which fortunately, works well as the ER4 is quite revealing of the setup behind it. I also recommend some Shure Black Foam Sleeves (a.k.a. Shure Olive Tips) for a slightly warmer presentation.
So what’s the difference between the ER4P and the ER4S? I am using the ER4P+impedance adapter as an approximation of the ER4S sound. First, the ER4S is harder to drive, and out of some portable players can sound a bit strained, while the ER4P sounds quite okay out of my Ipod Nano. However, both of them including the ER4P won’t really shine until I paired them with a better setup than direct to the Ipod Nano. The ER4S has a more emphasized and apparent treble than the ER4P, which is good since they have some good treble. It also improves upon the strong points of the ER4P (imaging, separation, speed, transparency, clarity, bass tightness). At the same time, quite a bit of warmth is lost in the mid and bass area when compared to the ER4P. I think this is an important point to consider, since the ER4S can sound quite clinical-sounding for a lot of people. The Nuforce uDAC is relatively warm sounding, and I was surprised at how clinical the ER4S sounded through it. The ER4S has more technical prowess than the ER4P, but it needs a good setup to really shine and further separate itself from the ER4P. I have heard an ER4S out of a proper desktop setup costing several times the price of an ER4S, and the harshness is almost gone, with all the goodness intact. Out of the uDAC, I prefer the ER4P for longer-term listening, though the ER4S sounds better in short doses.
In summary, when imagining the sound of the ER4, think about heightened or maybe even hyped sense of clarity, detail, separation. This kind of sound can be a bit tiring, but it is a very unique presentation, that is peerless among other IEMs and headphones I have tried. While the sound may not be suitable for everyone, over the years, it has gained quite a large following, and from my own experience, the ER4 sound can indeed become very addictive. When I first started with this hobby few years back, I bought lots of IEMs, but in the end, the ER4 prevailed, and I sold off all my other IEMs, not because I thought the ER4 was the best, it’s just because their presentation stood out and couldn’t be found in my other IEMs. I haven’t tried some of the newer IEMs like the Ortofon or Audio Technica’s high-ends, however, in the realm of Westone, Shure, and Ultimate Ears offerings, the ER4 has a very distinct sound.
Nowadays, I own and enjoy a completely different IEM in the Eterna, but the ER4’s instrument separation, quickness, articulation, and presentation of detail brought me to the STAX Lambdas, and I can definitely see some similarities.