The Beyerdynamic DT 1770 PRO MKII is 30Ω at 95.0 dB/mW; the Beyerdynamic DT 990 Edition (600Ω) is 600Ω at 96.0 dB (no reference unit printed). This page covers what they ask of an amplifier, not how they sound.
The DT 1770 PRO MKII needs 1.0 dB more than the DT 990 Edition (600Ω) to reach the same loudness — 3.2 mW against 2.5 mW.
| Specification | DT 1770 PRO MKII | DT 990 Edition (600Ω) |
|---|---|---|
| Impedance | 30 Ω | 600 Ω |
| Sensitivity | 95.0 dB/mW | 96.0 dB |
| Sensitivity (voltage) | 110.2 dB/V | 98.2 dB/V |
| Power for 100 dB | 3.2 mW | 2.5 mW |
| Voltage for 100 dB | 0.31 V | 1.23 V |
| Current for 100 dB | 10.3 mA | 2.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.75 Ω | 75.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 266 |
One caution before reading the rows. Beyerdynamic DT 990 Edition (600Ω) 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.
14 of the 280 sources have the power for the DT 1770 PRO MKII but not for the DT 990 Edition (600Ω) — Apple USB-C dongle (US), Apple USB-C dongle (EU), JadeAudio JA11, 11 more.
34 sources are low enough in output impedance for the DT 990 Edition (600Ω) under the one-eighth rule but not for the DT 1770 PRO MKII (Zoom AMS-22, Audient EVO 4, ART HeadAmp 4 Pro, 31 more).
266 of the 280 sources here reach 100 dB on both.
The DT 990 Edition (600Ω) is more demanding than 98% of the 567 non-electrostatic models in this database; the DT 1770 PRO MKII than 75%.
| dB SPL | DT 1770 PRO MKII power | DT 1770 PRO MKII voltage | DT 990 Edition (600Ω) power | DT 990 Edition (600Ω) voltage |
|---|---|---|---|---|
| 80 | 0.03 mW | 31 mV | 0.03 mW | 0.12 V |
| 85 | 0.10 mW | 55 mV | 0.08 mW | 0.22 V |
| 90 | 0.32 mW | 97 mV | 0.25 mW | 0.39 V |
| 95 | 1.0 mW | 0.17 V | 0.79 mW | 0.69 V |
| 100 | 3.2 mW | 0.31 V | 2.5 mW | 1.23 V |
| 105 | 10 mW | 0.55 V | 7.9 mW | 2.18 V |
| Source | Price | Headroom, DT 1770 PRO MKII | Headroom, DT 990 Edition (600Ω) | Output impedance | Noise |
|---|---|---|---|---|---|
| FiiO KA11 | $29 | 18.1 dB | 6.4 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 15.0 dB | 3.0 dB | 0.6 Ω | 1.0 µV |
| iBasso DC03 Pro | $69 | 14.6 dB | 3.2 dB | 0.12 Ω | 0.9 µV |
Of the 280 sources here, 266 reach 100 dB on both. 67 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 67 is the FiiO KA11, at $29. It leaves 18.1 dB of headroom on the DT 1770 PRO MKII and 6.4 dB on the DT 990 Edition (600Ω), its output impedance is 0.7 Ω against a one-eighth limit of 3.75 Ω and 75.00 Ω, and its noise figure puts the hiss floor 25 dB and 37 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| DT 1770 PRO MKII | 5-40,000 Hz | not printed | not printed |
| DT 990 Edition (600Ω) | 5 - 35.000 Hz | not printed | not printed |
Beyerdynamic prints 5-40,000 Hz for the DT 1770 PRO MKII and 5 - 35.000 Hz for the DT 990 Edition (600Ω).
DT 990 Edition (600Ω): Beyerdynamic prints one range for the whole DT 990 Edition 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 DT 1770 PRO MKII and Beyerdynamic DT 990 Edition (600Ω). 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.