Is it possible to move source file around in the tracker? Source audio file contains some milliseconds of silence before kick hits (screenshot), so I would just hope to “nudge” all file to bar 1 or bar 2. Method with “Find tempo…”, to drag start of bar 2 to the first kick does not work, because bar 1 then becomes to short (above 400 bmp). 
Superior Drummer 3 version: 3.2.4Operating system: Windows 10