AC adapter more wattage than required issues
You appear to be looking at the section on unregulated adapters. It's best to pick an adapter that (at least) meets or somewhat exceeds the current ratings on the original adapter. 

If you use an unregulated adapter that is rated for a huge amount greater than the original, the average output voltage can be much higher than expected by the designer, and the life of the product can be compromised due to excessive heating.