"This is caused by the MP3-format:
The mp3-format is a kind of compression with some loss of data, i.e. not the whole samples are stored, but - expressed in a simple way - some kind of "frequency curves", i.e. the mp3-encoder analyses a certain range of data and then stores the "frequency curves" for this range.
If now e.g. a live recording is stored in parts - one part in the first file, the following part in the second file - and compressed to the mp3-format, the encoding process is resetted for the second file - so the frequence curves (the end of the first file and the beginning of the second) don't match exactly.
In addition most mp3-files are "frame orientated", i.e. the encoder sometimes adds empty samples to the end of a file to get a whole frame at the end.
To put it together: Unfortunately it is not possible to always reconstruct the original data 100%-ly out of two mp3-files, that contain parts of continuous data.
If you want to work with continouos data, you must save all tracks into ONE mp3-file or use the wave-format."
So, the silences are "inside" the MP3 file. You can't avoid them with only setting pauses to zero. You need to edit the files.
The easiest way for me is using Feurio Track Editor. Simply select the position of the end (with the help of zoom) and press "Set end position". (The project settings must be configured to "Do not insert pauses between tracks - round track markers")
This editor is non-destructive, so the original files are not modified.
Of course, the result can't be perfect because of the MP3 format as explained before, but it sounds very well (no audible problem usually).