the 3.5mm jack can be used with any headphone it will automatically upscale to 7.1 but only via cable

Hello and thank you for your question.

You can use the 3.5mm jack connection with any headphones that use this connection. You can also use the audio functions (equalizer, surround) via the CORSAIR iCUE software.

Kind regards - Your CORSAIR Support

Yes and no: other headphones with the 3mm jack also work, but then the Corsair software cannot be used. This is not an obstacle for me, but those who appreciate the equaliser will miss it.