audioOS 9.9.15.5.1 (build 19L580) is an official Apple over-the-air update for the HomePod, released on 2022-05-25T17:16:56Z. The update package is 183.24 MB. This is a delta (partial) update that requires 15.4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fb883e083a60a6a2536b28878655b2d1f8d641df.zip.