audioOS 9.9.15.5.1 (build 19L580) is an official Apple over-the-air update for the HomePod, released on 2022-05-25T17:16:54Z. The update package is 543.75 MB. This is a delta (partial) update that requires 15.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a3b0be7a88aa9c272c35ad0e8011e07141652f77.zip.