The Kiwi Ears Orchestra II is 15Ω at 110.0 dB/mW; the Kiwi Ears Quartet is 32Ω at 110.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
In amplifier terms these two are the same headphone. The gap between what they need for 100 dB is under half a decibel, which is smaller than the step between two clicks of most volume controls.
| Specification | Orchestra II | Quartet |
|---|---|---|
| Impedance | 15 Ω | 32 Ω |
| Sensitivity | 110.0 dB/mW | 110.0 dB/mW |
| Sensitivity (voltage) | 128.2 dB/V | 124.9 dB/V |
| Power for 100 dB | 0.10 mW | 0.10 mW |
| Voltage for 100 dB | 39 mV | 57 mV |
| Current for 100 dB | 2.6 mA | 1.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.88 Ω | 4.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
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.
3 sources are low enough in output impedance for the Quartet under the one-eighth rule but not for the Orchestra II (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
9 sources stay below the audible-hiss threshold with the Quartet but cross it with the Orchestra II (Grace Design m900, FiiO M33 R2R, Schiit Lyr 5, 6 more).
280 of the 280 sources here reach 100 dB on both.
The Quartet is more demanding than 15% of the 567 non-electrostatic models in this database; the Orchestra II than 6%.
| dB SPL | Orchestra II power | Orchestra II voltage | Quartet power | Quartet voltage |
|---|---|---|---|---|
| 80 | 1.0 µW | 4 mV | 1.0 µW | 6 mV |
| 85 | 3.2 µW | 7 mV | 3.2 µW | 10 mV |
| 90 | 0.01 mW | 12 mV | 0.01 mW | 18 mV |
| 95 | 0.03 mW | 22 mV | 0.03 mW | 32 mV |
| 100 | 0.10 mW | 39 mV | 0.10 mW | 57 mV |
| 105 | 0.32 mW | 69 mV | 0.32 mW | 0.10 V |
| Source | Price | Headroom, Orchestra II | Headroom, Quartet | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 21.5 dB | 24.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 33.6 dB | 33.0 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 30.5 dB | 30.0 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 53 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 53 is the JadeAudio JA11, at $20. It leaves 21.5 dB of headroom on the Orchestra II and 24.8 dB on the Quartet, its output impedance is 0.5 Ω against a one-eighth limit of 1.88 Ω and 4.00 Ω, and its noise figure puts the hiss floor 7 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 |
|---|---|---|---|
| Orchestra II | 20Hz-20KHz | not printed | not printed |
| Quartet | 20Hz-20kHz | not printed | not printed |
Kiwi Ears prints 20Hz-20KHz for the Orchestra II and 20Hz-20kHz for the Quartet.
Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.
Not a measurement; maker by maker.
Both have a page of their own. In full: Kiwi Ears Orchestra II and Kiwi Ears Quartet. Every figure on this page comes from what Kiwi Ears published, or is derived from it — what that maker publishes, counted.