ASIO, WHAT NOW?

I just downloaded foobar 2000. And I noticed an improvement in the music that I listened to over the internet, YiuTube.

But,I already have my entire digital music list that I downloaded from the YouTube before foobar in a folder which are mp4.

Now my question is; Will foobar 2000 have any effect on the music I already have in my files when I listen to them?

I have media human audio converter to convert the mp4 files to WAV.

Do I have to convert all my files to WAV and then listen to them through foobar 2000?