Both are dongles, $149 against $140. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The Tanchjim LUNA reaches 100 dB on 565 of the 567 models here, the FiiO KA17 on 564.
| Specification | FiiO KA17 | Tanchjim LUNA |
|---|---|---|
| Power into 32Ω | 140 mW | 285 mW |
| Power into 150Ω | 34 mW | 80 mW |
| Power into 300Ω | 20 mW | 54 mW |
| Power into 600Ω | 10.0 mW | 27 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | 2.0 µV | 1.3 µV |
| Price | $149 | $140 |
| Headphones it reaches 100 dB on out of 567 | 564 | 565 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
| Load | FiiO KA17 | Tanchjim LUNA |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Published |
| 600 Ω | Derived | Derived |
Both makers publish a power rating, which is less common than the table above makes it look: of the 280 sources here, 209 publish a figure at at least one load and only 2 publish one at all four. FiiO KA17 publishes at 32 Ω and at 300 Ω; Tanchjim LUNA at 32 Ω and at 300 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
1 headphone reaches 100 dB on the Tanchjim LUNA but not on the FiiO KA17 — Symphonium Crimson.
5 headphones stay below the audible-hiss threshold on the Tanchjim LUNA but cross it on the FiiO KA17 (64 Audio Fourte, Campfire Audio Clara, Shure SE846, 2 more).
564 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Sennheiser HD 600: Tanchjim LUNA has +9 dB of headroom there against +5 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.
Hiss is this source’s own noise, in decibels SPL, in that headphone — not a rating. Below about 20 dB SPL it is under the threshold of hearing in a quiet room; a negative figure means it is far below it.
| Headphone | Impedance | Needs | FiiO KA17 headroom | Tanchjim LUNA headroom | FiiO KA17 hiss | Tanchjim LUNA hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB | +34 dB | 20 dB | 17 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB | +14 dB | 0 dB | -3 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +19 dB | +23 dB | -1 dB | -5 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB | +20 dB | -6 dB | -10 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +12 dB | +15 dB | -7 dB | -11 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +9 dB | +13 dB | -13 dB | -16 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB | +9 dB | -17 dB | -21 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +2 dB | +5 dB | -19 dB | -23 dB |
The FiiO KA17 costs $9 more than the Tanchjim LUNA, and on these three axes the money buys nothing: among the 567 models here there is not one that the FiiO KA17 handles and the Tanchjim LUNA does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Tanchjim LUNA drives one model to 100 dB and keeps 5 below the audible-hiss threshold that the FiiO KA17 does not.
Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: FiiO KA17 and Tanchjim LUNA. Or put either against your own headphones in the source comparison tool.