Both are Bluetooth receivers, $109 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 BTR5 2021 reaches 100 dB on 563 of the 567 models here, the Qudelix 5K on 561.
| Specification | FiiO BTR5 2021 | Qudelix 5K |
|---|---|---|
| Power into 32Ω | 80 mW | 125 mW |
| Power into 150Ω | 17 mW | 27 mW |
| Power into 300Ω | 8.5 mW | 13 mW |
| Power into 600Ω | 4.3 mW | 6.7 mW |
| Output impedance | 1.0 Ω | 0.4 Ω unverified |
| Output noise | 2.0 µV | 3 µV unverified |
| Price | $109 | $109 |
| Headphones it reaches 100 dB on out of 567 | 563 | 561 |
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.
3 headphones reach 100 dB on the FiiO BTR5 2021 but not on the Qudelix 5K — Moondrop COSMO, Symphonium Helios, Symphonium Zenith.
1 headphone reaches 100 dB on the Qudelix 5K but not on the FiiO BTR5 2021 — HiFiMAN Susvara.
560 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 BTR5 2021 and Qudelix 5K. Or put either against your own headphones in the source comparison tool.