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 is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
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.
9 sources stay below the audible-hiss threshold with the Q5 Pro but cross it with the K5 (Grace Design m900, FiiO K17, FiiO K19, 6 more).
280 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: 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.