The Austrian Audio Hi-X25BT is 25Ω. Its maker prints a sensitivity of 113.0 dB and never says whether that is per milliwatt or per volt, so this page reads it as per milliwatt — on that reading it needs 0.05 mW to reach 100 dB SPL, or 35 mV across the drivers. If the figure is really per volt, it needs far more.
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.
This maker printed a decibel figure and no reference unit, so the number above is shown exactly as printed. Everything below reads it as per milliwatt, which is the commoner convention on a sheet that omits the unit — if it is really per volt, this headphone is about 16 dB harder to drive than the rest of this page assumes. The converter explains the difference.
Austrian Audio publishes a sensitivity of 113 dB and does not state whether that is per milliwatt or per volt — the spec sheet simply stops at the number.
Both readings are given here so you can judge for yourself. If that 113 dB is per milliwatt, the figures on this page are right as they stand. If it is per volt, the real sensitivity is 97.0 dB/mW — 16 dB lower at 25Ω — and everything above understates what these need by that much. The per-milliwatt reading is the one shown, because it is the more common convention on a spec sheet that omits the unit; treat it as an indication rather than a specification.
The maker adds a power recommendation of its own: Max Input Power: 150mW
Source: austrian.audio. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency range | 12Hz – 24kHZ | not printed | not printed |
Austrian Audio prints 12Hz – 24kHZ for the Austrian Audio Hi-X25BT, under the heading “Frequency range”. Source: austrian.audio.
No tolerance is printed with it, so “12Hz – 24kHZ” says nothing about how loud this headphone actually is at 12 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 | 6 mV | 0.3 mA |
| 95 dB SPL | normal listening | 0.02 mW | 20 mV | 0.8 mA |
| 100 dB SPL | loud listening | 0.05 mW | 35 mV | 1.4 mA |
| 105 dB SPL | very loud | 0.16 mW | 63 mV | 2.5 mA |
| 110 dB SPL | peaks on dynamic music | 0.50 mW | 0.11 V | 4.5 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 25Ω 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 25Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| FiiO SnowSky Tiny A | USB dongle | $22 | 37 mW | +29 dB | Comfortable |
| FiiO SnowSky Tiny B | USB dongle | $22 | 44 mW | +29 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 75 mW | +32 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 164 mW | +35 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 164 mW | +35 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 108 mW | +33 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 55 mW | +30 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 55 mW | +30 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 53 mW | +30 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 51 mW | +30 dB | Comfortable |
| DUNU DTC 480 | USB dongle | $70 | 51 mW | +30 dB | Comfortable |
| EPZ TP35 Pro | USB dongle | $70 | 88 mW | +32 dB | Comfortable |
| Aiyima A2 Pro | desktop DAC/amp | $75 | 117 mW | +34 dB | Comfortable |
| ddHiFi TC35Pro (Eye2) | USB dongle | $76 | 51 mW | +30 dB | Comfortable |
| ddHiFi TC44 Pro E2 | USB dongle | $99 | 195 mW | +36 dB | Comfortable |
Hiss. At 129.0 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 37 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 25Ω these want a source output impedance below 3.12Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.
25Ω · 97.0 dB/mW · Easy
See requirements →25Ω · 102.0 dB/mW · Easy
See requirements →25Ω · 94.0 dB/mW · Easy
See requirements →20Ω · 112.0 dB/mW · Easy
See requirements →38Ω · 115.0 dB/mW · Easy
See requirements →21Ω · 112.0 dB/mW · Easy
See requirements →Compared with its stablemates: vs Hi-X15 · vs Hi-X20 · vs Hi-X55 · vs Hi-X60 · vs Hi-X65 · vs The Arranger · vs The Composer.