The 64 Audio U12t is 12.6Ω at 108.0 dB/mW; the Campfire Audio Andromeda 2020 is 9Ω at 94.0 dB (no figure from the maker at all). This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
The Campfire Audio Andromeda 2020 needs 14.0 dB more than the 64 Audio U12t to reach the same loudness — 4.0 mW against 0.16 mW.
| Specification | 64 Audio U12t | Campfire Audio Andromeda 2020 |
|---|---|---|
| Impedance | 12.6 Ω | 9 Ω |
| Sensitivity | 108.0 dB/mW | 94.0 dB |
| Sensitivity (voltage) | 127.0 dB/V | 114.5 dB/V |
| Power for 100 dB | 0.16 mW | 4.0 mW |
| Voltage for 100 dB | 45 mV | 0.19 V |
| Current for 100 dB | 3.5 mA | 21.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.57 Ω | 1.12 Ω |
| Sources that reach 100 dB out of 280 | 280 | 279 |
One caution before reading the rows. For Campfire Audio Andromeda 2020 the maker publishes no sensitivity figure at all. The number in the table was collected when this database was first built and has never been traced to a manufacturer document, so treat every row below it as an estimate rather than a specification.
1 of the 280 sources has the power for the 64 Audio U12t but not for the Campfire Audio Andromeda 2020 — Steinberg UR22C.
6 sources are low enough in output impedance for the 64 Audio U12t under the one-eighth rule but not for the Campfire Audio Andromeda 2020 (FiiO K11, FiiO BTR7, FiiO M11S, 3 more).
16 sources stay below the audible-hiss threshold with the Campfire Audio Andromeda 2020 but cross it with the 64 Audio U12t (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 13 more).
279 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The Campfire Audio Andromeda 2020 is more demanding than 56% of the 567 non-electrostatic models in this database; the 64 Audio U12t than 8%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | 64 Audio U12t power | 64 Audio U12t voltage | Campfire Audio Andromeda 2020 power | Campfire Audio Andromeda 2020 voltage |
|---|---|---|---|---|
| 80 | 1.6 µW | 4 mV | 0.04 mW | 19 mV |
| 85 | 5.0 µW | 8 mV | 0.13 mW | 34 mV |
| 90 | 0.02 mW | 14 mV | 0.40 mW | 60 mV |
| 95 | 0.05 mW | 25 mV | 1.3 mW | 0.11 V |
| 100 | 0.16 mW | 45 mV | 4.0 mW | 0.19 V |
| 105 | 0.50 mW | 79 mV | 13 mW | 0.34 V |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, 64 Audio U12t | Headroom, Campfire Audio Andromeda 2020 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 18.7 dB | 3.3 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 30.9 dB | 15.4 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 27.8 dB | 12.3 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 279 reach 100 dB on both. That is the easy axis. 48 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 rest either fail one of those or never printed the number at all, and 207 of them are in the second group.
The cheapest of the 48 is the JadeAudio JA11, at $20. It leaves 18.7 dB of headroom on the 64 Audio U12t and 3.3 dB on the Campfire Audio Andromeda 2020, its output impedance is 0.5 Ω against a one-eighth limit of 1.57 Ω and 1.12 Ω, and its noise figure puts the hiss floor 8 dB and 21 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| 64 Audio U12t | 10 Hz – 20 kHz | not printed | not printed |
| Campfire Audio Andromeda 2020 | nothing printed | — | — |
64 Audio prints 10 Hz – 20 kHz for the U12t. Campfire Audio prints nothing at all for the Andromeda 2020.
So one side of this comparison has a frequency-response number and the other does not — which changes less than it looks. The range printed for the 64 Audio U12t comes with no tolerance beside it, and a range without a ±dB figure says nothing about how loud the headphone is at either end of it: thirty decibels down at the bottom and the sentence would still be true. On the only reading that would have made it a specification, the two sheets say the same amount: nothing.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: 64 Audio U12t and Campfire Audio Andromeda 2020. Each figure on this page is labelled on those pages with where it came from, including the ones 64 Audio and Campfire Audio never published — what 64 Audio publishes and what Campfire Audio publishes, both counted.