Between the ER4XR and IE 900, the ER4XR comes out ahead in several specs, while the IE 900 wins on impedance and sensitivity. Overall, the ER4XR scores 39.7 and the IE 900 scores 66.4 on our Mars Score.
Which should you buy?
The IE 900 is the clear pick on raw spec strength, leading by 26.7 points on the Mars Score. The margin is wide enough that the underdog only makes sense if its individual strengths line up with what you specifically need.
The ER4XR doesn't pull ahead on any single popular-comparison spec — its strengths sit in the spec table groups rather than the headline advantages.
Pick the IE 900 if you care most about impedance and sensitivity. Its strongest claims are impedance, sensitivity.
Both ship with comparable driver count, detachable cable, so those specs don't separate the two — focus on the differences below.
Bottom line: the IE 900 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Etymotic - ER4XR wins
- No decisive advantages.
Why Sennheiser - IE 900 wins
- ▲Impedance — 29.00 Ω less. 16 vs 45.
- ▲Sensitivity — 25.51% more. 123 dB vs 98 dB.
Spec comparison
Drivers
| Spec | Etymotic - ER4XR | Sennheiser - IE 900 |
|---|---|---|
| Driver count | 1 | 1 |
| Driver types | Balanced Armature | Dynamic (X3R) |
| Impedanceⓘ | 45 Ω | 16 Ωlead |
| Sensitivityⓘ | 98 dB | 123 dBlead |
Build
| Spec | Etymotic - ER4XR | Sennheiser - IE 900 |
|---|---|---|
| Detachable cable | true | true |
| Connector | MMCX | MMCX |
Frequently asked
Spec-level deep dives
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