Short answer
Both are desktop amplifiers, $499 against $699.
The Singxer SA-1 reaches 100 dB on 567 of the 567 models here, the Schiit Valhalla 3 on 566.
| Specification | Schiit Valhalla 3 | Singxer SA-1 |
|---|---|---|
| Power into 32Ω | 750 mW | 5.5 W |
| Power into 150Ω | 286 mW | 1.6 W |
| Power into 300Ω | 250 mW | 785 mW |
| Power into 600Ω | 125 mW | 380 mW |
| Output impedance | 25 Ω | 1.4 Ω |
| Output noise | 6.32 µV | 0.3 µV |
| Price | $499 | $699 |
| Headphones it reaches 100 dB on out of 567 | 566 | 567 |
| Load | Schiit Valhalla 3 | Singxer SA-1 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Published |
Both makers publish a power rating. Schiit Valhalla 3 publishes at 32 Ω and at 300 Ω; Singxer SA-1 at 32 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 300 Ω only the Schiit Valhalla 3 figure is the maker’s own and at 600 Ω only the Singxer SA-1 figure is the maker’s own. On those rows the derived number is the one to doubt first.
1 headphone reaches 100 dB on the Singxer SA-1 but not on the Schiit Valhalla 3 — Symphonium Titan.
484 headphones are left alone by the Singxer SA-1 under the one-eighth rule but coloured by the Schiit Valhalla 3 (64 Audio Solo, 64 Audio U12t, 7Hz Legato, 481 more).
102 headphones stay below the audible-hiss threshold on the Singxer SA-1 but cross it on the Schiit Valhalla 3 (64 Audio Fourte, 64 Audio Nio, 64 Audio U12t, 99 more).
566 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: Singxer SA-1 has +32 dB of headroom there against +17 dB. 14 dB is about 27 times the power, which matters for peaks rather than for how loud the music sits.
Hiss below about 20 dB SPL is inaudible in a quiet room.
| Headphone | Impedance | Needs | Schiit Valhalla 3 headroom | Singxer SA-1 headroom | Schiit Valhalla 3 hiss | Singxer SA-1 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +37 dB damping | +52 dB damping | 30 dB | 4 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +17 dB damping | +32 dB damping | 10 dB | -16 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +27 dB damping | +36 dB | 9 dB | -18 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +26 dB | +32 dB | 4 dB | -22 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +19 dB damping | +29 dB | 3 dB | -23 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +20 dB | +25 dB | -3 dB | -29 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +16 dB | +21 dB | -7 dB | -33 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +10 dB damping | +18 dB | -9 dB | -35 dB |
The Singxer SA-1 costs $200 more than the Schiit Valhalla 3. Out of the 567 models here, that difference buys 1 more model driven to 100 dB, 484 more models left alone under the one-eighth rule and 102 more models kept below the audible-hiss threshold.
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: Schiit Valhalla 3 and Singxer SA-1.