Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Etymotic - ER4XR | Moondrop - Aria 2 |
|---|---|---|
| Sensitivity | 98 dB | 122 dB |
| Impedance | 45 Ω | 32 Ω |
Between the ER4XR and Aria 2, the ER4XR comes out ahead in several specs, while the Aria 2 wins on sensitivity / impedance. Overall, the ER4XR scores 39.7 and the Aria 2 scores 65.4 on our Mars Score.
Which should you buy?
The Aria 2 is the clear pick on raw spec strength, leading by 25.7 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 does not pull ahead on any single popular-comparison spec — its strengths sit in the spec-table groups rather than the headline advantages.
Pick the Aria 2 if you care most about sensitivity / impedance. Its strongest claims are sensitivity, impedance. The single most decisive one: Sensitivity — 24.49% more. 122 dB vs 98 dB.
Both ship with comparable driver count, detachable cable, so those specs do not separate the two — focus on the differences below.
Bottom line: the Aria 2 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Which should you buy: Etymotic - ER4XR or Moondrop - Aria 2?
Moondrop - Aria 2 leads the current Mars Score by 25.7 points.The more useful decision is the trade-off behind that result: compare impedance, sensitivity against the way you will actually use the product.
Choose Etymotic - ER4XR if…
Etymotic - ER4XR does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
Choose Moondrop - Aria 2 if…
Moondrop - Aria 2 has the measurable edge on sensitivity db, impedance ohm.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why Etymotic - ER4XR wins
- No decisive advantages.
Why Moondrop - Aria 2 wins
- ▲Sensitivity — 24.49% more. 122 dB vs 98 dB.
- ▲Impedance — 13.00 Ω less. 32 vs 45.
Spec comparison
Drivers
| Spec | Etymotic - ER4XR | Moondrop - Aria 2 |
|---|---|---|
| Driver count | 1 | 1 |
| Driver types | Balanced Armature | Dynamic |
| Impedanceⓘ | 45 Ω | 32 Ωlead |
| Sensitivityⓘ | 98 dB | 122 dBlead |
Build
| Spec | Etymotic - ER4XR | Moondrop - Aria 2 |
|---|---|---|
| Detachable cable | true | true |
| Connector | MMCX | 0.78mm 2-pinlead |