Between the IE 600 and IER-M9, the IE 600 comes out ahead in sensitivity, while the IER-M9 wins on driver count. Overall, the IE 600 scores 61.5 and the IER-M9 scores 54.5 on our Mars Score.
Which should you buy?
The IE 600 edges ahead on the Mars Score (61.5 vs 54.5), but the 7.0-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the IE 600 if you care most about sensitivity. The biggest gaps in its favor are sensitivity.
Pick the IER-M9 if you care most about driver count. Its strongest claims are driver count.
Both ship with comparable impedance, detachable cable, so those specs don't separate the two — focus on the differences below.
Bottom line: the IE 600 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Sennheiser - IE 600 wins
- ▲Sensitivity — 14.56% more. 118 dB vs 103 dB.
Why Sony - IER-M9 wins
- ▲Driver count — 4.00 more. 5 vs 1.
Spec comparison
Drivers
| Spec | Sennheiser - IE 600 | Sony - IER-M9 |
|---|---|---|
| Driver count | 1 | 5lead |
| Driver types | Dynamic (TrueResponse) | 5 Balanced Armature |
| Impedanceⓘ | 18 Ω | 18 Ω |
| Sensitivityⓘ | 118 dBlead | 103 dB |
Build
| Spec | Sennheiser - IE 600 | Sony - IER-M9 |
|---|---|---|
| Detachable cable | true | true |
| Connector | MMCX | MMCX |
Spec-level deep dives
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