Hi
In the past I have replaced iPod battery’s with higher mAh battery’s and it went quite well however I’d left very little space inside of the iPod so I’m not too sure the battery would fit nicely inside of the beats X as they have such Little room even with the original battery and even if it did fit I can’t imagine it would be very safe because when the Samsung galaxy note 7batterys were exploding it was due to having almost no space so if I were you I would see if anyone else has done it but if you are the first person to do it I probably wouldn’t due to the potential safety concerns
I hope this answers your question
Thanks:)