Etymotic ER2XR and ER2SE publish identical numbers. So does the calculator tell them apart?
«Impedance: 15 Ohms @ 1kHz / Sensitivity: 96 dB @ 1kHz, 1mW» appears on both the ER2XR and the ER2SE page. Etymotic labels its scale, so the unit is not in doubt — the model is. On a MiniFuse 1 the answer is +6.4 dB and a damping ratio of 1.5, for both.
Signal Chain Compatibility Matrix
Select gear and parameters for live gain, impedance and SPL calculations.
Input Equipment Setup
PASS: Optimal Signal Chain
Requires minimum +60dB of clean pre-amp gain. Most budget entry interfaces max out at +50dB to +56dB and introduce hiss at max pot. An inline preamp booster (Cloudlifter CL-1 / FetHead) is strongly recommended.
The interface preamp provides sufficient headroom.
$538
$405
-25%Tonal & acoustic characteristics: Flat, wide-range frequency response for clean music and speech. Smooth, warm acoustic character with air-suspension shock isolation.
Technical advisory: With +69dB max gain, the Gen 4 Solo can drive demanding dynamics like the Shure SM7B natively without requiring an external inline booster.
Physical Interconnect Topology
Shure SM7B
Direct Cable Connection (No Intermediate Box)
1x Shielded Balanced XLR Cable (3-Pin XLR Male to XLR Female)
Focusrite Scarlett Solo (Gen 4)
Host: Apple MacBook Pro (M1/M2/M3/M4)
Etymotic is one of the few makers that names the reference inside the row — and that is exactly why this claim is about something else. The unit is certain; what the numbers cannot tell you is which model you are holding.
The ER2XR page prints «Impedance: 15 Ohms @ 1kHz» and «Sensitivity: 96 dB @ 1kHz, 1mW». The ER2SE page prints the identical pair. XR is the extended-bass tuning, SE the flat one; they are sold as different products at the same price.
As published, on a MiniFuse 1. S_V = 96 + 10·lg(1000/15) = 114.24 dB/V. A 110 dB peak needs 0.614 V — and at 15 Ω that is 40.92 mA and 25.12 mW, the highest current draw in this batch. Arturia publishes «Phones … Power @ 33ohm: 137mW», i.e. 2.13 V, and «Output impedance: 10Ω». The divider leaves 1.278 V at the earphone: 116.4 dB SPL, +6.4 dB of level — but a damping ratio of 15/10 = 1.5 against a rule of 8, so the verdict is damping risk.
What the other reading would cost. If that «1mW» label were missing and you read 96 as dB/V, the peak would need 5.012 V, 334.12 mA and 1674.59 mW; the MiniFuse would land at 98.1 dB SPL, −11.9 dB, too quiet. The label is worth 18.2 dB here — more than on any other headphone in this batch, because 10·lg(1000/15) grows as the impedance falls. Low-impedance in-ears are exactly where an unlabelled sensitivity does the most damage, and they are also where makers most often omit it.
How to judge — and what cannot be judged. The unit needs no judgement: Etymotic writes it. The model does. The same duplication repeats one tier up: the ER4SR and ER4XR pages both print 45 Ohms and 98 dB @ 1 kHz, 1 mW. Etymotic states the difference between SR and XR is acoustic, not electrical, which may well be true — but it means these figures cannot identify a model, and any calculator, ours included, must return the same answer for both members of a pair. It does, and it should.
The pearl: on this interface the two Etymotics land 0.1 dB apart in level and three times apart in tonal risk. The ER4XR (45 Ω, 98 dB/mW) computes to +6.3 dB against the ER2XR's +6.4 — indistinguishable — while their damping ratios are 4.5 and 1.5. Both are below 8, so both are at risk, but the 15 Ω model is at risk three times over. Move both to a FiiO KA13 (1.7 Ω) and the picture inverts: the ER2XR is comfortable at +5.0 dB with a ratio of 8.8, while the ER4XR drops to +2.9 dB — enough, without headroom. The cheaper dongle is the better source, and no spec sheet says so.