The Grado GS3000x is 38Ω at 99.8 dB/mW; the Grado Signature S550 is 38Ω at 112.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The GS3000x needs 12.2 dB more than the Signature S550 to reach the same loudness — 1.0 mW against 0.06 mW.
| Specification | GS3000x | Signature S550 |
|---|---|---|
| Impedance | 38 Ω | 38 Ω |
| Sensitivity | 99.8 dB/mW | 112.0 dB/mW |
| Sensitivity (voltage) | 114.0 dB/V | 126.2 dB/V |
| Power for 100 dB | 1.0 mW | 0.06 mW |
| Voltage for 100 dB | 0.20 V | 49 mV |
| Current for 100 dB | 5.2 mA | 1.3 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.75 Ω | 4.75 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
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.
16 sources stay below the audible-hiss threshold with the GS3000x but cross it with the Signature S550 (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 13 more).
280 of the 280 sources here reach 100 dB on both.
The GS3000x is more demanding than 58% of the 567 non-electrostatic models in this database; the Signature S550 than 10%.
| dB SPL | GS3000x power | GS3000x voltage | Signature S550 power | Signature S550 voltage |
|---|---|---|---|---|
| 80 | 0.01 mW | 20 mV | 0.6 µW | 5 mV |
| 85 | 0.03 mW | 35 mV | 2.0 µW | 9 mV |
| 90 | 0.10 mW | 63 mV | 6.3 µW | 15 mV |
| 95 | 0.33 mW | 0.11 V | 0.02 mW | 28 mV |
| 100 | 1.0 mW | 0.20 V | 0.06 mW | 49 mV |
| 105 | 3.3 mW | 0.35 V | 0.20 mW | 87 mV |
| Source | Price | Headroom, GS3000x | Headroom, Signature S550 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 13.8 dB | 26.0 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 22.1 dB | 34.3 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 19.0 dB | 31.2 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 55 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 55 is the JadeAudio JA11, at $20. It leaves 13.8 dB of headroom on the GS3000x and 26.0 dB on the Signature S550, its output impedance is 0.5 Ω against a one-eighth limit of 4.75 Ω for both, and its noise figure puts the hiss floor 21 dB and 9 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| GS3000x | 4 - 51,000 hz | not printed | not printed |
| Signature S550 | 6Hz - 44kHz | not printed | not printed |
Grado prints 4 - 51,000 hz for the GS3000x and 6Hz - 44kHz for the Signature S550.
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: Grado GS3000x and Grado Signature S550. Every figure on this page comes from what Grado published, or is derived from it — what that maker publishes, counted.