Good question. The pine will only draw the current it needs. In theory you could use a 5v 200A supply and be fine.
I should add one caveat, if you do use something with more than 5A keep in mind you should keep in mind that the slightest short is likely going to be quite sparky and dramatic.
I should add one caveat, if you do use something with more than 5A keep in mind you should keep in mind that the slightest short is likely going to be quite sparky and dramatic.