Hi all,
First post here!
Just thought some of you might be interested in this: I have written a simple command line tool for tagging DSF files.
With the tool you can edit most ID3v2 tags. Picture import/export is also supported.
This is NOT an application with a nice graphical user interface! It's entirely text based which means you have to be pretty comfortable with UNIX shell interface to use it effectively.
Precompiled binary for Mac OS X is available here. It should run on Linux and Windows as well but you'll need to compile from source by yourself.
For documentation (and source code) please check out https://github.com/pekingduck/metadsf
Although I have tested the tool on my small DSD collection (around 100G) without any problems, it'd be wise for you to back up first!
Suggestions, bug reports or comments are welcome.