This page does not review anything EPZ 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 |
|---|---|---|---|
| 530 Pro | 32 Ω | 110.0 dB | Unit not stated |
| K5 | 28 Ω | 114.0 dB | Unit not stated |
| Q5 Pro | 24 Ω | 109.0 dB | Unit not stated |
| Star One | 64 Ω | 100.1 dB/mW | Converted from per volt |
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.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| 530 Pro | 20Hz–20kHz | not printed | not printed |
| K5 | 20Hz–20kHz | not printed | not printed |
| Q5 Pro | 20Hz–20kHz | not printed | not printed |
| Star One | 20Hz - 40kHz | not printed | not printed |
EPZ prints a frequency range for all 4 models here whose sheets have been read.
Not one of those ranges comes with a tolerance in decibels. Without a ±dB figure a range says nothing about how loud the headphone is at either end of it, which puts EPZ with the majority: of the 490 models across this database whose maker prints a range, 58 print the tolerance.
Every range stands under the same heading: “Frequency Response”.
No measurement is published here — only what was printed. The whole count, maker by maker, is in the frequency response audit.
The hardest of the 4 to drive is the EPZ Star One: 0.98 mW and 0.25 V for a 100 dB SPL peak. Their impedances run from 24 to 64 Ω, which matters because the voltage a headphone wants rises with impedance while the power falls.
280 of the 280 sources here reach 100 dB on all 4, and the cheapest of them is the Apple USB-C dongle (EU) at $9. “Reaches” means the maker’s own published power figure is enough at that load; it is not a judgement of how it sounds.
On hiss the count is smaller, because most of the industry does not publish a noise figure at all: of the 83 sources here that do, 61 stay under the threshold of hearing on all 4 of their in-ears. The one to watch is the EPZ K5 at 130 dB/V — the more sensitive the in-ear, the more of the amplifier’s own noise you hear.
Their lowest impedance is the EPZ Q5 Pro at 24 Ω, so a source wants an output impedance at or below 3.0 Ω to satisfy the one-eighth rule on everything they make. 134 of the 169 sources that publish an output impedance manage that.
These counts use figures the source makers published themselves. A product that publishes nothing is not counted as a pass anywhere above, which is why the three numbers differ so much. The collection matcher runs the same arithmetic over whatever you actually own.
| Product | Into 32Ω | Output impedance | Output noise |
|---|---|---|---|
| EPZ TP35 Pro | 112 mW | not published | not published |
| EPZ TP50 | 121 mW | not published | 1.0 µV |
Power decides whether it gets loud enough, output impedance decides whether it tilts the response of a multi-driver in-ear, and the noise figure decides whether you hear hiss with sensitive ones. All three fit on one line of a spec sheet; most of the industry prints one of them.
EPZ publishes a power figure at a stated load on 2 of 2, output impedance on 0, a noise figure on 1. Of the 8 power figures this site displays for them at 32, 150, 300 and 600 Ω: 2 printed by EPZ at that exact load, 6 worked out by holding output voltage steady across loads.
Rather less than half of what this site says about EPZ came from them. The rest is arithmetic, and it is marked as arithmetic on every page.
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.