Setting up a Multi-Output Device in your Mac's System Preferences is the best way to play sound through both speakers and headphones at the same time.

• Connect your Mac to the speakers and headphones.
• Open the Applications folder in Finder.
• Open Audio MIDI Setup from Utilities.
• Click the Plus button in the lower-left corner and select 'Create Multi-Output Device.'
• Right-click Multi-Output Device in the left panel and select 'Use This Device for Sound Output.'
• Check the boxes next to the devices you want to utilise in the right panel. Check the box next to Built-in Output if the device is a wired one.
• In the dropdown box, select a Master Device.
• By checking Drift Correction, you can choose a Slave Device.
• Open System Preferences and click on the Sound tab.
• Select Multi-Output Device from the Output tab.

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