The built-in 3.5mm headphone jack on the left side of the new iMac features impedance detection and adaptive voltage output, and the computer now has a built-in digital-to-analog converter with support for sample rates of up to 96 kHz, allowing for users to listen to high-fidelity, full-resolution audio with supported headphones.
Apple's list of all Macs that support high-impedance headphones, and have a built-in hardware digital-to-analog converter:
iMac introduced in 2023 MacBook Air introduced in 2022 or later MacBook Pro introduced in 2021 or later Mac mini introduced in 2023 Mac Studio introduced in 2022 or later Mac Pro introduced in 2023The new iMac launched today after being introduced at Apple's event last week. Key new features include the M3 chip, Wi-Fi 6E, and Bluetooth 5.3. The all-in-one desktop computer has the same design as the 2021 model with the M1 chip.