The EPZ K5 is 28Ω at 114.0 dB (no reference unit printed); the EPZ Q5 Pro is 24Ω at 109.0 dB (no reference unit printed). This page covers what they ask of an amplifier, not how they sound.
The Q5 Pro needs 5.0 dB more than the K5 to reach the same loudness — 0.13 mW against 0.04 mW.
| Specification | K5 | Q5 Pro |
|---|---|---|
| Impedance | 28 Ω | 24 Ω |
| Sensitivity | 114.0 dB | 109.0 dB |
| Sensitivity (voltage) | 129.5 dB/V | 125.2 dB/V |
| Power for 100 dB | 0.04 mW | 0.13 mW |
| Voltage for 100 dB | 33 mV | 55 mV |
| Current for 100 dB | 1.2 mA | 2.3 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.50 Ω | 3.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. EPZ K5 and EPZ Q5 Pro printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, each of them needs far more than the table says. Why the two readings differ by so much.
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
11 sources stay below the audible-hiss threshold with the Q5 Pro but cross it with the K5 (Fosi Audio SK02, Grace Design m900, Schiit Lyr 5, 8 more).
280 of the 280 sources here reach 100 dB on both.
The Q5 Pro is more demanding than 13% of the 567 non-electrostatic models in this database; the K5 than 4%.
| dB SPL | K5 power | K5 voltage | Q5 Pro power | Q5 Pro voltage |
|---|---|---|---|---|
| 80 | 0.4 µW | 3 mV | 1.3 µW | 5 mV |
| 85 | 1.3 µW | 6 mV | 4.0 µW | 10 mV |
| 90 | 4.0 µW | 11 mV | 0.01 mW | 17 mV |
| 95 | 0.01 mW | 19 mV | 0.04 mW | 31 mV |
| 100 | 0.04 mW | 33 mV | 0.13 mW | 55 mV |
| 105 | 0.13 mW | 59 mV | 0.40 mW | 98 mV |
| Source | Price | Headroom, K5 | Headroom, Q5 Pro | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 28.2 dB | 22.5 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 37.1 dB | 32.3 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 34.1 dB | 29.2 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 51 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 51 is the JadeAudio JA11, at $20. It leaves 28.2 dB of headroom on the K5 and 22.5 dB on the Q5 Pro, its output impedance is 0.5 Ω against a one-eighth limit of 3.50 Ω and 3.00 Ω, and its noise figure puts the hiss floor 6 dB and 10 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| K5 | 20Hz–20kHz | not printed | not printed |
| Q5 Pro | 20Hz–20kHz | not printed | not printed |
EPZ prints the same thing for both the K5 and the Q5 Pro: 20Hz–20kHz.
Neither range has a tolerance printed beside it, so the matching numbers say little.
Not a measurement; maker by maker.
Both have a page of their own. In full: EPZ K5 and EPZ Q5 Pro. Each figure on this page is labelled on those pages with where it came from, including the ones EPZ never published — what that maker publishes, counted.