To reduce http requests and minify static files download, it is recommended to concatenate and minify all JavaScript/CSS files used by single page.
Does it make difference?
1) Minify all javascript files and then concatenate them;
2) Concatenate all javascript files and then minify them.
Minifying several smaller files into one big file (through
>>redirect, for example) appeals by the fact that good minifyers will complain if they find a syntax error in one of those files. You will immediately see in which file.