Well, Cassie is wrong!
Audio Hijack Pro provides a function, called "
Silence Monitor", which looks for silence/no sound in your recording and does a predefined or custom action whenever it detects silence!!!
It lets you remove a recording, stop the process, start a new file, etc..
You can activate it in the "Recording" tab under "Silence Menu".
Furthermore, in exactly the same menu, above "Silence Monitor", there's a category called "
Limits", which may also come in handy, because it let's you start a new song or stop the recording at a precise moment in time or after a certain amount of disc space has been used!
Note however, that both ways are not perfect!
If you go with the "Silence Monitor", you should set the silence between the tracks in iTunes to 3-5 seconds, and configure Audio Hijack to only split pauses as big as 3-5 seconds! This should prevent Audio Hijack from splitting episodes of silence in some songs!
"Limits" is not very practical in your case, because the length and size of every track differs. You are only able to record one track at a time with this function!
If you need to do some manual splitting, editing, and removing, there are a couple of software tools available!
For my Audio Hijack needs, I use
Fission! Garage Band might also do the job though.