In theory, any charger with the correct voltage and higher than required current supply would work. In practise, you need to check to make sure the power supply is "regulated" and there is a higher possibility that power supplies with very high current output are "unregulated". Unregulated PSUs would put out about 30% higher voltage than specified when lightly loaded and may be a hazard to the X5--although I remember it having overvoltage protection, better safe than sorry
10 years ago I earned my current custom title by doing something stupid with power supply units
Hahaha I guess I'll be sticking with Samsung's 5V2A charger then. Better safe than sorry.