Why the start of sounds gets cut off on AirPlay
Updated 2026-10-06
The start of a sound gets lost or delayed because AirPlay suspends the stream when your Mac goes quiet, then negotiates a new stream when sound resumes, which takes about 370 ms. Playing inaudible noise keeps the stream open. Digital silence doesn't work, because the driver detects it.
What's happening
macOS's AirPlay driver watches for silence. When there's none to play, it suspends the stream; when sound starts again, it negotiates a brand-new remote stream. The Preroll README describes this as the bottleneck that appears once the 2000 ms buffer is lowered, and puts the renegotiation at about 370 ms.
That's why a notification chime or the first click after a pause feels later than the rest, and why very short sounds can seem clipped.
Keeping the stream awake
Pure digital silence doesn't help: the driver has enableSilenceDetection and enableNonZeroPCMSampleDetection, so it can tell. Preroll's approach, which Lagless uses, is to play never-zero random noise at −78 dBFS, far below what you can hear, so the stream never looks idle.
In Lagless, this is Keep Speaker Awake. It only plays while your output is an AirPlay device, and stops when you switch to anything else.
Questions
Will I hear the noise?
At −78 dBFS it's far below normal listening levels. If you turn a speaker right up in a silent room you might, so you can switch it off.
Does it use battery?
A little, like any audio playing. It stops when you're not on AirPlay.