The Austrian Audio Hi-X25BT is 25Ω at 113.0 dB (no reference unit printed); the Austrian Audio Hi-X65 is 25Ω at 94.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The Hi-X65 needs 19.0 dB more than the Hi-X25BT to reach the same loudness — 4.0 mW against 0.05 mW.
| Specification | Hi-X25BT | Hi-X65 |
|---|---|---|
| Impedance | 25 Ω | 25 Ω |
| Sensitivity | 113.0 dB | 94.0 dB/mW |
| Sensitivity (voltage) | 129.0 dB/V | 110.0 dB/V |
| Power for 100 dB | 0.05 mW | 4.0 mW |
| Voltage for 100 dB | 35 mV | 0.32 V |
| Current for 100 dB | 1.4 mA | 12.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.12 Ω | 3.12 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Austrian Audio Hi-X25BT 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.
20 sources stay below the audible-hiss threshold with the Hi-X65 but cross it with the Hi-X25BT (FiiO BTR11, Fosi Audio SK02, FiiO K11 R2R, 17 more).
280 of the 280 sources here reach 100 dB on both.
The Hi-X65 is more demanding than 77% of the 567 non-electrostatic models in this database; the Hi-X25BT than 5%.
| dB SPL | Hi-X25BT power | Hi-X25BT voltage | Hi-X65 power | Hi-X65 voltage |
|---|---|---|---|---|
| 80 | 0.5 µW | 4 mV | 0.04 mW | 32 mV |
| 85 | 1.6 µW | 6 mV | 0.13 mW | 56 mV |
| 90 | 5.0 µW | 11 mV | 0.40 mW | 100 mV |
| 95 | 0.02 mW | 20 mV | 1.3 mW | 0.18 V |
| 100 | 0.05 mW | 35 mV | 4.0 mW | 0.32 V |
| 105 | 0.16 mW | 63 mV | 13 mW | 0.56 V |
| Source | Price | Headroom, Hi-X25BT | Headroom, Hi-X65 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 26.7 dB | 7.7 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 36.2 dB | 17.2 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 33.2 dB | 14.2 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 26.7 dB of headroom on the Hi-X25BT and 7.7 dB on the Hi-X65, its output impedance is 0.5 Ω against a one-eighth limit of 3.12 Ω for both, and its noise figure puts the hiss floor 6 dB and 25 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| Hi-X25BT | 12Hz – 24kHZ | not printed | not printed |
| Hi-X65 | 5Hz - 28kHz | not printed | not printed |
Austrian Audio prints 12Hz – 24kHZ for the Hi-X25BT and 5Hz - 28kHz for the Hi-X65.
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: Austrian Audio Hi-X25BT and Austrian Audio Hi-X65. Each figure on this page is labelled on those pages with where it came from, including the ones Austrian Audio never published — what that maker publishes, counted.