DAZ formats (for example .dsf) can only be created in the original software and no other. So if you need to convert .obj files (3D objects) to .dsf files, you have to use DAZ Studio software. There seems to be no other way for this conversion.
Convert 3D object graphics to DAZ Studio DSF file format 3D file.
We have found 2 software records in our database eligible for .obj to .dsf file format conversion.
Microsoft Windows software - convert obj to dsf on Windows
A 3D animation software
Convert from obj file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned obj to dsf. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert obj to dsf on OS X
A Mac version of the popular modeling tool