Voices aren't scheduled immediately, so some audio is missed.

[nathanleiby]

It takes a few beats before you hear sounds because of schedule ahead logic

Examples:

• Change the loop (including first run).. press play.. its sounds aren't scheduled yet.
• Click change a single beat, the voices aren't scheduled immediately.

Today, audio scheduling happens "just in time" as the clock progresses, but perhaps it should also depend on when notes are added/removed.

Relatedly, we might want to track handles for all scheduled sounds so we can unschedule them before/during play if they're removed

let handle = manager.play(sound.with_settings(sound_settings))?;
// track the handles...
// if need to stop...
handle.stop()