Both are portable players, $1799 against $1999. 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 FiiO M17 reaches 100 dB on 567 of the 567 models here, the HiBy R8 II on 565.
| Specification | FiiO M17 | HiBy R8 II |
|---|---|---|
| Power into 32Ω | 500 mW | 225 mW |
| Power into 150Ω | 115 mW | 48 mW |
| Power into 300Ω | 63 mW | 24 mW |
| Power into 600Ω | 32 mW | 12 mW |
| Output impedance | 1 Ω | 1 Ω |
| Output noise | 3.5 µV | 3.2 µV |
| Price | $1799 | $1999 |
| Headphones it reaches 100 dB on out of 567 | 567 | 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 M17 | HiBy R8 II |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 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 M17 publishes at 32 Ω and at 300 Ω; HiBy R8 II at 32 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.
So the two columns are not equally firm row by row: at 300 Ω only the FiiO M17 figure is the maker’s own. On those rows the derived number is the one to doubt first.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
2 headphones reach 100 dB on the FiiO M17 but not on the HiBy R8 II — Moondrop PARA, Symphonium Titan.
4 headphones stay below the audible-hiss threshold on the HiBy R8 II but cross it on the FiiO M17 (Audio-Technica ATH-CKS1100, EPZ K5, Grado Signature S750, 1 more).
565 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 Shure SE846: FiiO M17 has +40 dB of headroom there against +32 dB. 8 dB is about 6.6 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 M17 headroom | HiBy R8 II headroom | FiiO M17 hiss | HiBy R8 II hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +40 dB | +32 dB | 25 dB | 25 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +20 dB | +12 dB | 5 dB | 5 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +25 dB | +21 dB | 3 dB | 3 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +21 dB | +17 dB | -1 dB | -2 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +19 dB | +13 dB | -2 dB | -3 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +14 dB | +10 dB | -8 dB | -9 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +10 dB | +6 dB | -12 dB | -13 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +7 dB | +4 dB | -14 dB | -15 dB |
The HiBy R8 II costs $200 more than the FiiO M17. Out of the 567 models here, that difference buys 4 more models kept below the audible-hiss threshold.
It does not run one way only: the cheaper FiiO M17 drives 2 models to 100 dB that the HiBy R8 II does not, which is the part worth checking against your own headphones before paying the difference.
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 M17 and HiBy R8 II. Or put either against your own headphones in the source comparison tool.