Both are Bluetooth receivers, $59 against $109. 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 BTR13 reaches 100 dB on 565 of the 567 models here, the FiiO BTR5 2021 on 563.
| Specification | FiiO BTR13 | FiiO BTR5 2021 |
|---|---|---|
| Power into 32Ω | 100 mW | 80 mW |
| Power into 150Ω | 21 mW | 17 mW |
| Power into 300Ω | 10.0 mW | 8.5 mW |
| Power into 600Ω | 5.0 mW | 4.3 mW |
| Output impedance | 0.6 Ω | 1.0 Ω |
| Output noise | 1.0 µV | 2.0 µV |
| Price | $59 | $109 |
| Headphones it reaches 100 dB on out of 567 | 565 | 563 |
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.
2 headphones reach 100 dB on the FiiO BTR13 but not on the FiiO BTR5 2021 — HiFiMAN Susvara, Symphonium Crimson.
14 headphones are left alone by the FiiO BTR13 under the one-eighth rule but coloured by the FiiO BTR5 2021 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 11 more).
5 headphones stay below the audible-hiss threshold on the FiiO BTR13 but cross it on the FiiO BTR5 2021 (64 Audio Fourte, Campfire Audio Clara, Shure SE846, 2 more).
563 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.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: FiiO BTR13 and FiiO BTR5 2021. Or put either against your own headphones in the source comparison tool.