Good news come fast today... thanks for all.
Still there is a last glitch that IMHO should be settled:
if you want to change something of the format of your mp3 and get rid of the originals, what you really want is TO REPLACE the originals with new file with the same name! Of course this not always the case, but at least for me it often is.
The problem is that now you can get rid of the originals when converting only if the latter have a different extensions, otherwise you will get the blocking message asking to change name or folder for the new files.
This is actually a bit incongruous: you should be able to choose the option in all cases, even when your conversion does not change the codec (i.e. the filename extension) but only some parameters of it (e.g. bitrate).
Maybe this will complicate the matter a bit on the technical side, since the program will have to create the converted file with a temp fake name, then delete the original, and finally rename the converted file with the original name. I hope this is not terrible....
