I found 2 things lol
DSF ( .DSF ) - File Extension Information
Extension: DSF ( . DSF )
Description:
DSF is the file extension for the Micrografx Designer v7.x file.
Dreamcast Sound Format is the proposed title of a digital music format for encoding Dreamcast music, similar to PlayStation Sound Format. So far, such a format has not been publicly released.
A DSF file contains a raw ARM7 sound program image which is loaded and copied to a specified address inside the program. The ARM7 then resets and executes the image.
DSF files can be loaded into a Winamp plugin called Highly Theoretical.
The only known publicly released set is Ikaruga, though a sample track from Skies of Arcadia is known to exist.