Is it just me, or is the "Sound Check" feature on iTunes and Ipods basically useless? I have this feature turned on when playing music but there is still significant variations in the sound output for different songs. Obviously not all songs in a playlist are from the same source (some off Itunes music store, some ripped from CD in AAC format, some downloaded MP3's etc etc) and therefore variations in song volume are to be expected. But isn't sound check meant to sort this out? These output variations are particularly annoying when playing tunes through external speakers. Barring going through every song in my library and adjusting it's individual output level, is there a solution to the shortcomings of the sound check feature?
Thanks for your input in advance.

Howard Holmes