Etymotic ER-4S
Etymotic’s legendary reference in-ear: flat, uncolored, and ruthlessly accurate, with the deepest isolation around.
Our take
The ER-4S is the measurement-grade IEM: near-flat, uncolored, and unflattering, with the deepest insertion and isolation of any in-ear. It trades fun for truth and comfort for accuracy. At 100 Ω it likes a little voltage. If you want a reference in your ears, this is the classic.
Measured on a Head Acoustics HMS II.3 artificial head — raw response, left/right averaged, normalized to 0 dB at 1 kHz. From the Sonic Temple Archive(2008–2014, one unit per model). Honest limits: seating variance runs ±0.4 dB in the mids to ±3.9 dB above 12 kHz, and open headphones read bass-light on this fixture — don’t read fine treble detail as settled. How we measure →
Common questions
Straight answers — the same ones our measurements support.
Does the Etymotic ER-4S need an amp?
It benefits from one: at 100 Ω it is higher-impedance than most IEMs and wants a bit of voltage.
Is the ER-4S bass-light?
It is neutral, not boosted, and needs a proper deep seal for full bass. With a good tip fit the low end is there, just honest.
If you like the ER-4S
Close on the graph, or a deliberate step in one direction.