The Kiwi Ears Halcyon is 29Ω with a sensitivity of 109.0 dB/mW, which is 124.4 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 0.13 mW, or 60 mV across the drivers.
That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 280 have at least 10 dB of headroom and another 0 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.
Sensitivity here is in dB per milliwatt. Why the unit matters.
Kiwi Ears publishes this directly as 109 dB ((at 1kHz/mW)), per milliwatt, so nothing was converted.
The maker adds a power recommendation of its own: Maximum Power Handling: 10mW
Source: kiwiears.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency Response Range | 10-42kHz | not printed | not printed |
Kiwi Ears prints 10-42kHz for the Kiwi Ears Halcyon, under the heading “Frequency Response Range”. Source: kiwiears.com.
No tolerance is printed with it, so “10-42kHz” says nothing about how loud this headphone actually is at 10 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.00 mW | 11 mV | 0.4 mA |
| 95 dB SPL | normal listening | 0.04 mW | 34 mV | 1.2 mA |
| 100 dB SPL | loud listening | 0.13 mW | 60 mV | 2.1 mA |
| 105 dB SPL | very loud | 0.40 mW | 0.11 V | 3.7 mA |
| 110 dB SPL | peaks on dynamic music | 1.3 mW | 0.19 V | 6.6 mA |
Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.
The 15 cheapest of the 280 sources here that reach 100 dB SPL into 29Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.
| Source | Type | Price | Power into 29Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| FiiO SnowSky Tiny A | USB dongle | $22 | 35 mW | +24 dB | Comfortable |
| FiiO SnowSky Tiny B | USB dongle | $22 | 38 mW | +25 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 75 mW | +28 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 190 mW | +32 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 190 mW | +32 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 125 mW | +30 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 63 mW | +27 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 63 mW | +27 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 62 mW | +27 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 59 mW | +27 dB | Comfortable |
| DUNU DTC 480 | USB dongle | $70 | 59 mW | +27 dB | Comfortable |
| EPZ TP35 Pro | USB dongle | $70 | 102 mW | +29 dB | Comfortable |
| Aiyima A2 Pro | desktop DAC/amp | $75 | 136 mW | +30 dB | Comfortable |
| ddHiFi TC35Pro (Eye2) | USB dongle | $76 | 59 mW | +27 dB | Comfortable |
| ddHiFi TC44 Pro E2 | USB dongle | $99 | 227 mW | +33 dB | Comfortable |
Hiss. At 124.4 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 32 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 29Ω these want a source output impedance below 3.62Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.
28Ω · 102.0 dB · Easy
See requirements →32Ω · 110.0 dB/mW · Easy
See requirements →32Ω · 110.0 dB/mW · Easy
See requirements →18Ω · 107.0 dB · Easy
See requirements →12Ω · 105.0 dB/mW · Easy
See requirements →35Ω · 110.0 dB · Easy
See requirements →Compared with its stablemates: vs Belle · vs KE4 · vs Orchestra II · vs Orchestra Lite.