The Beyerdynamic DJ 300 PRO X is 48Ω at 115.0 dB (no reference unit printed); the Beyerdynamic DT 990 Pro (80Ω) is 80Ω at 96.0 dB (no reference unit printed). This page covers what they ask of an amplifier, not how they sound.
The DT 990 Pro (80Ω) needs 19.0 dB more than the DJ 300 PRO X to reach the same loudness — 2.5 mW against 0.03 mW.
| Specification | DJ 300 PRO X | DT 990 Pro (80Ω) |
|---|---|---|
| Impedance | 48 Ω | 80 Ω |
| Sensitivity | 115.0 dB | 96.0 dB |
| Sensitivity (voltage) | 128.2 dB/V | 107.0 dB/V |
| Power for 100 dB | 0.03 mW | 2.5 mW |
| Voltage for 100 dB | 39 mV | 0.45 V |
| Current for 100 dB | 0.8 mA | 5.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 6.00 Ω | 10.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Beyerdynamic DJ 300 PRO X and Beyerdynamic DT 990 Pro (80Ω) printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, each of them 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 are low enough in output impedance for the DT 990 Pro (80Ω) under the one-eighth rule but not for the DJ 300 PRO X (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 6 more).
19 sources stay below the audible-hiss threshold with the DT 990 Pro (80Ω) but cross it with the DJ 300 PRO X (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 16 more).
280 of the 280 sources here reach 100 dB on both.
The DT 990 Pro (80Ω) is more demanding than 84% of the 567 non-electrostatic models in this database; the DJ 300 PRO X than 6%.
| dB SPL | DJ 300 PRO X power | DJ 300 PRO X voltage | DT 990 Pro (80Ω) power | DT 990 Pro (80Ω) voltage |
|---|---|---|---|---|
| 80 | 0.3 µW | 4 mV | 0.03 mW | 45 mV |
| 85 | 1.0 µW | 7 mV | 0.08 mW | 80 mV |
| 90 | 3.2 µW | 12 mV | 0.25 mW | 0.14 V |
| 95 | 0.01 mW | 22 mV | 0.79 mW | 0.25 V |
| 100 | 0.03 mW | 39 mV | 2.5 mW | 0.45 V |
| 105 | 0.10 mW | 69 mV | 7.9 mW | 0.80 V |
| Source | Price | Headroom, DJ 300 PRO X | Headroom, DT 990 Pro (80Ω) | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 28.0 dB | 6.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 36.3 dB | 15.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 33.2 dB | 12.0 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 28.0 dB of headroom on the DJ 300 PRO X and 6.8 dB on the DT 990 Pro (80Ω), its output impedance is 0.5 Ω against a one-eighth limit of 6.00 Ω and 10.00 Ω, and its noise figure puts the hiss floor 7 dB and 28 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| DJ 300 PRO X | 5 - 35,000 Hz | not printed | not printed |
| DT 990 Pro (80Ω) | 5 - 35.000 Hz | not printed | not printed |
Beyerdynamic prints 5 - 35,000 Hz for the DJ 300 PRO X and 5 - 35.000 Hz for the DT 990 Pro (80Ω).
DT 990 Pro (80Ω): Beyerdynamic prints one range for the whole DT family page, the same figure for every impedance version.
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: Beyerdynamic DJ 300 PRO X and Beyerdynamic DT 990 Pro (80Ω). Each figure on this page is labelled on those pages with where it came from, including the ones Beyerdynamic never published — what that maker publishes, counted.