Short answer
Both are Bluetooth receivers, both at $109.
The FiiO BTR5 2021 reaches 100 dB on 563 of the 567 models here, the HiBy W5 on 557.
| Specification | FiiO BTR5 2021 | HiBy W5 |
|---|---|---|
| Power into 32Ω | 80 mW | 80 mW |
| Power into 150Ω | 17 mW | 17 mW |
| Power into 300Ω | 8.5 mW | 8.5 mW |
| Power into 600Ω | 4.3 mW | 4.3 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | 2.0 µV | not published |
| Price | $109 | $109 |
| Headphones it reaches 100 dB on out of 567 | 563 | 557 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | FiiO BTR5 2021 | HiBy W5 |
|---|---|---|
| Socket | 2.5mm | no separate rating |
| Power into 32Ω | 240 mW | — |
| Power into 300Ω | 26 mW derived | — |
| Output impedance | 2.0 Ω | — |
| Output noise | 2.2 µV | — |
| Headphones it reaches 100 dB on out of 567 | 565 | — |
Only the FiiO BTR5 2021 has a separate balanced rating from its maker; through it, it reaches 100 dB on 565 of the 567 models here. The HiBy W5 may still have a balanced socket — its spec sheet simply gives no figure for one, so there is nothing to put beside it. Derived figures are worked out from the loads the maker did publish.
| Load | FiiO BTR5 2021 | HiBy W5 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. FiiO BTR5 2021 publishes at 32 Ω; HiBy W5 at 32 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
6 headphones reach 100 dB on the FiiO BTR5 2021 but not on the HiBy W5 — Moondrop COSMO, Moondrop PARA 2, Moondrop VENUS, 3 more.
557 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Campfire Audio Andromeda 2020: FiiO BTR5 2021 has +11 dB of headroom there against +8 dB. 4 dB is about 2.2 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for HiBy W5 because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | FiiO BTR5 2021 headroom | HiBy W5 headroom | FiiO BTR5 2021 hiss | HiBy W5 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +31 dB | +28 dB | 20 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +11 dB | +8 dB | 0 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +17 dB | +17 dB | -1 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +12 dB | +12 dB | -6 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +10 dB | +9 dB | -7 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +5 dB | +5 dB | -13 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +1 dB | +1 dB | -17 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -1 dB | -1 dB | -19 dB | not published |
These two cost the same, $109, so price settles nothing. Out of the 567 models here, the FiiO BTR5 2021 drives 6 models to 100 dB — and on the other side there is no such advantage at all.
Only published figures count here; blank axes are counted separately.
Each in full: FiiO BTR5 2021 and HiBy W5.