An answer, and a question.
First, I too puzzled about the function of the input slider control. Then I found that I could use the volume control on the cassette tape player from which I was sourcing the music to adjust the input level on SoundTrax. The slider control in the software does nothing that I can see, but perhaps it depends on the input source.
Next, the question: kaloochi's answer is helpful, but doesn't go all the way. Like jcham, I have ended up with one long track with obvious quiet bits. I've put in the splits using the automatic detector in the SoundTrax wizard. However, when I export the project to MP4 it comes out as a single file. Now, I want to listen to the music in my iPod and I think that means I need to have each track as a single file, grouped as an album. How do I achieve this? Do I need to select each song, copy it out into its own track, and export it separately? Or is there an automatic way of doing this?
All help gratefully received. I do not find the Nero user guides especially helpful here!