This page does not review anything Westone makes. It counts one thing: how much of what this database says about their products came out of their own documents, and how much had to be worked out or left blank.
| Model | Impedance | Sensitivity | Source of the figure |
|---|---|---|---|
| MACH 10 | 80 Ω | 103.0 dB | Unit not stated |
| MACH 20 | 96 Ω | 110.0 dB | Unit not stated |
| MACH 60 | 35 Ω | 100.0 dB | Unit not stated |
| MACH 80 | 66 Ω | 104.0 dB | Unit not stated |
| Pro X10 | 19 Ω | 114.0 dB/mW | Published per mW |
Impedance is almost always printed. Sensitivity is the one that goes wrong, because a decibel figure means two very different things depending on whether it is per milliwatt or per volt — about five decibels apart at 300 Ω and eighteen at 16 Ω. The conversion is here.
Very little of what this site says about Westone came from them. That is not an accusation about how their products sound — it is a statement about their paperwork, and it is the reason those pages carry so many qualifiers.
The rule used here is the same for every maker and is described on the manufacturer index. Every figure behind it can be opened on the product page it came from, with the document it came from linked.