Between the U12t and IER-M9, the U12t comes out ahead in sensitivity and driver count, while the IER-M9 wins on several specs. Overall, the U12t scores 79.3 and the IER-M9 scores 54.5 on our Mars Score.
Which should you buy?
The U12t is the clear pick on raw spec strength, leading by 24.8 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.
Pick the U12t if you care most about sensitivity and driver count. The biggest gaps in its favor are sensitivity, driver count, impedance.
The IER-M9 similarly doesn't carry a headline advantage on the popular specs — look at the full table for category-specific deltas.
Both ship with comparable detachable cable, so those specs don't separate the two — focus on the differences below.
Bottom line: the U12t is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why 64 Audio - U12t wins
- ▲Sensitivity — 11.65% more. 115 dB vs 103 dB.
- ▲Driver count — 7.00 more. 12 vs 5.
- ▲Impedance — 6.00 Ω less. 12 vs 18.
Why Sony - IER-M9 wins
- No decisive advantages.
Spec comparison
Drivers
| Spec | 64 Audio - U12t | Sony - IER-M9 |
|---|---|---|
| Driver count | 12lead | 5 |
| Driver types | 12 Balanced Armature | 5 Balanced Armature |
| Impedanceⓘ | 12 Ωlead | 18 Ω |
| Sensitivityⓘ | 115 dBlead | 103 dB |
Build
| Spec | 64 Audio - U12t | Sony - IER-M9 |
|---|---|---|
| Detachable cable | true | true |
| Connector | 2-pinlead | MMCX |
Spec-level deep dives
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