Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | 64 Audio - U12t | Sony - IER-M9 |
|---|---|---|
| Sensitivity | 115 dB | 103 dB |
| Driver count | 12 | 5 |
| Impedance | 12 Ω | 18 Ω |
Between the U12t and IER-M9, the U12t comes out ahead in sensitivity / 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 / driver count. The biggest gaps in its favor are sensitivity, driver count, impedance. The single most decisive one: Sensitivity — 11.65% more. 115 dB vs 103 dB.
The IER-M9 similarly does not 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 do not 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.
Which should you buy: 64 Audio - U12t or Sony - IER-M9?
64 Audio - U12t leads the current Mars Score by 24.8 points.The more useful decision is the trade-off behind that result: compare driver count, impedance, sensitivity against the way you will actually use the product.
Choose 64 Audio - U12t if…
64 Audio - U12t has the measurable edge on sensitivity db, driver count, impedance ohm.
Choose Sony - IER-M9 if…
Sony - IER-M9 does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
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 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 |