According to Detectorpro they are all 150 ohm.
If you got the WS4 and the adapter clip you can plug your GGs or any other set in to hear how they sound including lower quality phones like the Koss UR30s that Minelab sends. It has been my experience that unless you need the noise canceling properties of full size headphones the backphones XP makes , both wired and wireless , deliver terrific sound with their 32 ohm speakers.
If you got the WS4 and the adapter clip you can plug your GGs or any other set in to hear how they sound including lower quality phones like the Koss UR30s that Minelab sends. It has been my experience that unless you need the noise canceling properties of full size headphones the backphones XP makes , both wired and wireless , deliver terrific sound with their 32 ohm speakers.