The Symphonium Helios is 8.5Ω at 83.3 dB/mW; the Symphonium Titan is 3.0Ω at 79.8 dB/mW. This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
The Titan needs 3.5 dB more than the Helios to reach the same loudness — 105 mW against 47 mW.
| Specification | Helios | Titan |
|---|---|---|
| Impedance | 8.5 Ω | 3.0 Ω |
| Sensitivity | 83.3 dB/mW | 79.8 dB/mW |
| Sensitivity (voltage) | 104.0 dB/V | 105.0 dB/V |
| Power for 100 dB | 47 mW | 105 mW |
| Voltage for 100 dB | 0.63 V | 0.56 V |
| Current for 100 dB | 74.2 mA | 186.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.06 Ω | 0.38 Ω |
| Sources that reach 100 dB out of 280 | 179 | 85 |
94 of the 280 sources have the power for the Helios but not for the Titan — FiiO KA11, ddHiFi TC35Air, ddHiFi TC35AL, 91 more.
67 sources are low enough in output impedance for the Helios under the one-eighth rule but not for the Titan (JadeAudio JA11, FiiO SnowSky Tiny A, FiiO SnowSky Tiny B, 64 more).
85 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Symphonium Helios and Symphonium Titan. Every figure on this page comes from what Symphonium published, or is derived from it — what that maker publishes, counted.