Both are desktop amplifiers, $600 against $599. 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 Topping A90 Discrete reaches 100 dB on 567 of the 567 models here, the Soncoz SGA1 on 566.
| Specification | Soncoz SGA1 | Topping A90 Discrete |
|---|---|---|
| Power into 32Ω | 407 mW | 2.0 W |
| Power into 150Ω | 207 mW | 480 mW |
| Power into 300Ω | 210 mW | 250 mW |
| Power into 600Ω | 105 mW | 125 mW |
| Output impedance | 0.1 Ω | 0.1 Ω |
| Output noise | 1.8 µV | 0.2 µV |
| Price | $600 | $599 |
| Headphones it reaches 100 dB on out of 567 | 566 | 567 |
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.
1 headphone reaches 100 dB on the Topping A90 Discrete but not on the Soncoz SGA1 — Symphonium Titan.
2 headphones stay below the audible-hiss threshold on the Topping A90 Discrete but cross it on the Soncoz SGA1 (Simgot EA500, Tanchjim EA FORCE).
566 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: Soncoz SGA1 and Topping A90 Discrete. Or put either against your own headphones in the source comparison tool.