Unusual audio jack

[punkrockmum]

All the documentation and info tells me the audio jack will take a standard 2.5 mm cable, but mine will not. I bought it second hand so I'm wondering if the jack was broken when I bought it. I'd like to be able to listen to music and watch movies with headphones. Is there any way around this or am I stuck with the adapter? I'd rather get a new jack because I want to charge it while watching.

Thanks

[xtatic5]

Standard headphones are 3.5mm. You'll need the adapter to use almost any headphones with this device.