Both are audio interfaces, $570 against $250. 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 Focusrite Scarlett 18i16 (4th Gen) reaches 100 dB on 553 of the 567 models here, the Focusrite Vocaster Two on 550.
| Specification | Focusrite Scarlett 18i16 (4th Gen) | Focusrite Vocaster Two |
|---|---|---|
| Power into 32Ω | 55 mW | 27 mW |
| Power into 150Ω | 27 mW | 10 mW |
| Power into 300Ω | 27 mW | 7.7 mW |
| Power into 600Ω | 14 mW | 3.8 mW |
| Output impedance | 11 Ω | not published |
| Output noise | not published | not published |
| Price | $570 | $250 |
| Headphones it reaches 100 dB on out of 567 | 553 | 550 |
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 Focusrite Scarlett 18i16 (4th Gen) but not on the Focusrite Vocaster Two — HiFiMAN Susvara Unveiled, Kinera Freya Vanir, Thieaudio Hype 10.
550 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: Focusrite Scarlett 18i16 (4th Gen) and Focusrite Vocaster Two. Or put either against your own headphones in the source comparison tool.