The FiiO FT5 is 36Ω with a sensitivity of 96.0 dB/mW, which is 110.4 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 2.5 mW, or 0.30 V 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, 270 have at least 10 dB of headroom and another 10 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.
FiiO publishes this directly as 96 dB/mW (@1kHz), per milliwatt, so nothing was converted.
The maker adds a power recommendation of its own: Max power input 2000mW (no minimum/recommended power published)
Source: fiio.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency response | 7Hz-40kHz | not printed | not printed |
FiiO prints 7Hz-40kHz for the FiiO FT5, under the heading “Frequency response”. Source: fiio.com.
No tolerance is printed with it, so “7Hz-40kHz” says nothing about how loud this headphone actually is at 7 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.08 mW | 53 mV | 1.5 mA |
| 95 dB SPL | normal listening | 0.79 mW | 0.17 V | 4.7 mA |
| 100 dB SPL | loud listening | 2.5 mW | 0.30 V | 8.4 mA |
| 105 dB SPL | very loud | 7.9 mW | 0.53 V | 14.9 mA |
| 110 dB SPL | peaks on dynamic music | 25 mW | 0.95 V | 26.4 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 36Ω 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 36Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| JadeAudio JA11 | USB dongle | $20 | 27 mW | +10 dB | Comfortable |
| FiiO SnowSky Tiny A | USB dongle | $22 | 30 mW | +11 dB | Comfortable |
| FiiO SnowSky Tiny B | USB dongle | $22 | 30 mW | +11 dB | Comfortable |
| Kiwi Ears Allegro Mini | USB dongle | $24 | 27 mW | +10 dB | Comfortable |
| FiiO KA11 | USB dongle | $29 | 178 mW | +19 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 67 mW | +14 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 187 mW | +19 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 187 mW | +19 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 123 mW | +17 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 62 mW | +14 dB | Comfortable |
| FiiO BTR13 | Bluetooth receiver | $59 | 89 mW | +15 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 63 mW | +14 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 60 mW | +14 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 58 mW | +14 dB | Comfortable |
| iBasso DC03 Pro | USB dongle | $69 | 87 mW | +15 dB | Comfortable |
Hiss. At 110.4 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 18 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 36Ω these want a source output impedance below 4.50Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.
32Ω · 98.0 dB/mW · Easy
See requirements →32Ω · 95.1 dB/mW · Easy
See requirements →32Ω · 88.1 dB/mW · Moderate
See requirements →18Ω · 93.0 dB/mW · Easy
See requirements →23Ω · 94.0 dB · Easy
See requirements →56Ω · 98.0 dB/mW · Easy
See requirements →Compared with its stablemates: vs FT1 · vs FT3 (350Ω) · vs JT1.