As others have mentioned, you will need a 1/8 to 1/4 adapter. However, the Equinox 800 comes with a ML 80 wireless (Bluetooth) headphone that has a built-in battery, and individual volume control as follows: The detector has its own volume control, and the headphone also has a volume control. It means that you can leave the detector's volume on the factory setting, and crank the headphone's volume as high as you want. If you still want more volume, then you can increase the detector's volume, too. But this ML 80 Bluetooth headphone is only included with the Equinox 800, and not the 600. Both the Equinox 800 and the 600 also come with an additional wireless module, with is a small Wi-Fi Stream (wireless) unit you can clip on your shirt or belt to be used on most wireless headphones that transmit on Wi-Fi Stream.
The advantage of using a wireless headphone like the one of the Equinox 800 is as follows: you aren't connected to the detector via a cable, so you can put the detector on the ground a couple of feet or more away from you to dig a target from the ground, and there is not a cable getting in the way or flapping around when you are swinging the detector or just walking.