So I've been using the Sound Check feature in iTunes for forever. It was recently that I started noticing that many of the new songs I've added (well over a thousand) are all quieter than the songs that I originally started added to my list (way back when iTunes first came out). And each time I add more songs it the volume overall slowly drops lower and lower. Now I know I could just adjust the levels manually, but this is with at least a thousand songs, and even then other songs are at random levels too. Is there any app that can fix this or some other suggestion?