Lagless vs Preroll
Updated 2026-10-06
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Lagless and Preroll both lower macOS's AirPlay buffer with the audioLatencyMs setting, and both keep the stream awake with inaudible noise. Preroll discovered and documented the mechanism and applies it with a standard admin prompt. Lagless uses a helper you approve once, adds presets, per-speaker memory and an undo, and lives in the menu bar.
At a glance
| Preroll | Lagless | |
|---|---|---|
| Mechanism | audioLatencyMs, root's preferences | Same |
| Keep-alive noise | Yes, −78 dBFS | Yes, −78 dBFS, AirPlay only |
| Changing the value | Admin prompt per change | One-time helper approval |
| Lowest value offered | Slider with manual entry | 350 ms (lower is silent) |
| Presets | – | Responsive, Balanced, Safe |
| Shows the speaker's live delay | – | Yes, before and after |
| Per-speaker memory | – | Yes |
| Price and licence | Free, MIT | Free, MIT |
Details of Preroll are from its README and notes; check them for its current features.
Credit where it's due
Preroll found the setting, worked out that only root's preferences are read, measured the 250 ms floor and designed the keep-alive. Lagless builds on that research.
Which to choose
- Pick Preroll if you want the original, prefer an admin prompt per change, or want its optional per-speaker switching helper.
- Pick Lagless if you want a menu bar app with presets, a live readout and no prompt after setup.