What does “DJ software can be controlled without using a special control disc” mean?
A “control disc” is a special disc for controlling the DJ software on the computer from the CDJ. This is a system used by other DJ software brands, which are sometimes sold with a special disc for controlling that DJ software. The DJ software can be operated by loading this special disc on the CDJ, without any other changes to the CDJ. (The signals of the special disc are input to the computer via a special box.) The CDJ-350 can be connected directly to the computer by USB, so there is no need for the control disc.