Short answer
Both are dongles, $210 against $229.
The Qudelix T71 reaches 100 dB on 566 of the 567 models here, the EPZ TP50 on 561.
| Specification | EPZ TP50 | Qudelix T71 |
|---|---|---|
| Power into 32Ω | 121 mW | 500 mW |
| Power into 150Ω | 26 mW | 107 mW |
| Power into 300Ω | 13 mW | 53 mW |
| Power into 600Ω | 6.5 mW | 27 mW |
| Output impedance | not published | 0.3 Ω unverified |
| Output noise | 1.0 µV | 2.5 µV unverified |
| Price | $210 | $229 |
| Headphones it reaches 100 dB on out of 567 | 561 | 566 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | EPZ TP50 | Qudelix T71 |
|---|---|---|
| Socket | 4.4mm | 2.5mm+4.4mm |
| Power into 32Ω | 240 mW | 2.0 W derived |
| Power into 300Ω | 26 mW derived | 213 mW derived |
| Output impedance | not published | not published |
| Output noise | 1.0 µV | not published |
| Headphones it reaches 100 dB on out of 567 | 565 | 567 |
Through the balanced sockets the Qudelix T71 reaches 100 dB on 567 of the 567 models here and the EPZ TP50 on 565. Derived figures are worked out from the loads the maker did publish.
| Load | EPZ TP50 | Qudelix T71 |
|---|---|---|
| 32 Ω | Published | Upper bound |
| 150 Ω | Derived | Upper bound |
| 300 Ω | Derived | Upper bound |
| 600 Ω | Derived | Upper bound |
These two columns are not the same kind of number, and that matters more than the gap between them. EPZ TP50 publishes a power rating (at 32 Ω); Qudelix T71 publishes no power figure at any load, only a maximum output voltage, so every milliwatt in its column is a ceiling worked out from that voltage.
A ceiling assumes the amplifier holds that voltage into the load, and nothing on Qudelix T71’s own sheet says it does. It is the most flattering reading available, and it is used here only because the alternative is a blank. Where the Qudelix T71 column looks the stronger of the two, treat the difference as unproven rather than measured. 24 of the 280 sources here are in that position, with no published power rating at any load.
5 headphones reach 100 dB on the Qudelix T71 but not on the EPZ TP50 — Moondrop COSMO, Moondrop PARA, Symphonium Crimson, 2 more.
561 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 Audeze LCD-2 Classic: Qudelix T71 has +25 dB of headroom there against +18 dB. 6 dB is about 4.1 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Qudelix T71 because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | EPZ TP50 headroom | Qudelix T71 headroom | EPZ TP50 hiss | Qudelix T71 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +29 dB | +35 dB | 14 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +9 dB | +15 dB | -6 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +18 dB | +25 dB | -7 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +14 dB | +20 dB | -12 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +11 dB | +17 dB | -13 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +7 dB | +13 dB | -19 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +3 dB | +9 dB | -23 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +1 dB | +7 dB | -25 dB | not published |
The Qudelix T71 costs $19 more than the EPZ TP50. Out of the 567 models here, that difference buys 5 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: EPZ TP50 and Qudelix T71.