Dolby Atmos not working when using aux cable or third part wired earbuds

Hey Dave778778,

We'd recommend reviewing this article for steps and requirements to use Dolby Atmos with iPhone: About Spatial Audio with Dolby Atmos in Apple Music - Apple Support

"Choose how to listen to Dolby Atmos on your iPhone or iPad

1. Update your iPhone or iPad to the latest version of iOS or iPadOS.
2. Go to Settings.
3. Tap Music.
4. Under Audio, tap Dolby Atmos. 
5. Choose Automatic, Always On, or Off.

If you choose Automatic, here’s what you need

Supported songs automatically play in Dolby Atmos when you're listening with:

• AirPods Pro, AirPods Max, AirPods (3rd generation), or Beats Fit Pro with Spatial Audio turned on
• AirPods (1st or 2nd generation)
• BeatsX, Beats Solo3 Wireless, Beats Studio3, Powerbeats3 Wireless, Beats Flex, Powerbeats Pro, Beats Solo Pro, or Beats Studio Buds
• Any Bluetooth headphones that you categorize as headphones on your iPhone or iPad
• The built-in speakers on an iPhone XS or later (except iPhone SE), iPad Pro 12.9-inch (3rd generation or later), iPad Pro 11-inch, or iPad Air (4th generation or later)

If you choose Always On, here’s what you need

If you want to use wired headphones, choose Always On."

Thanks!