The Kiwi Ears Belle is 32Ω at 103.0 dB (no reference unit printed); the Kiwi Ears Quartet is 32Ω at 110.0 dB/mW. 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 Belle needs 7.0 dB more than the Quartet to reach the same loudness — 0.50 mW against 0.10 mW.
| Specification | Belle | Quartet |
|---|---|---|
| Impedance | 32 Ω | 32 Ω |
| Sensitivity | 103.0 dB | 110.0 dB/mW |
| Sensitivity (voltage) | 117.9 dB/V | 124.9 dB/V |
| Power for 100 dB | 0.50 mW | 0.10 mW |
| Voltage for 100 dB | 0.13 V | 57 mV |
| Current for 100 dB | 4.0 mA | 1.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.00 Ω | 4.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Kiwi Ears Belle printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model 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 Belle but cross it with the Quartet (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 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.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The Belle is more demanding than 41% of the 567 non-electrostatic models in this database; the Quartet than 15%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | Belle power | Belle voltage | Quartet power | Quartet voltage |
|---|---|---|---|---|
| 80 | 5.0 µW | 13 mV | 1.0 µW | 6 mV |
| 85 | 0.02 mW | 23 mV | 3.2 µW | 10 mV |
| 90 | 0.05 mW | 40 mV | 0.01 mW | 18 mV |
| 95 | 0.16 mW | 71 mV | 0.03 mW | 32 mV |
| 100 | 0.50 mW | 0.13 V | 0.10 mW | 57 mV |
| 105 | 1.6 mW | 0.23 V | 0.32 mW | 0.10 V |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, Belle | Headroom, Quartet | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 17.8 dB | 24.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 26.0 dB | 33.0 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 23.0 dB | 30.0 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. That is the easy axis. 62 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 rest either fail one of those or never printed the number at all, and 208 of them are in the second group.
The cheapest of the 62 is the JadeAudio JA11, at $20. It leaves 17.8 dB of headroom on the Belle and 24.8 dB on the Quartet, its output impedance is 0.5 Ω against a one-eighth limit of 4.00 Ω for both, and its noise figure puts the hiss floor 17 dB and 10 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| Belle | 20Hz-20kHz | not printed | not printed |
| Quartet | 20Hz-20kHz | not printed | not printed |
Kiwi Ears prints the same thing for both the Belle and the Quartet: 20Hz-20kHz.
Neither range has a tolerance printed beside it, and that is the whole of what this section can tell you. The two sheets print the same range, which is itself a hint about how much the number is worth. A ±dB figure is what turns a range into a specification, and of the 490 models whose maker prints a range, 58 print it.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Kiwi Ears Belle and Kiwi Ears Quartet. Each figure on this page is labelled on those pages with where it came from, including the ones Kiwi Ears never published — what that maker publishes, counted.