This is a relic of the gentoo proaudio overlay at tuxfamily.org.
For the new generation gentoo proaudio overlay, take a look at: https://github.com/domichel/proaudio-gentoo
The non working ebuilds (not compiling, broken dependencies, dead projects with non available sources) are completely removed from tuxfamily and will not be imported here.
You will find here only ebuilds that was working when importing them, but I don't use these software, have limited time. It can also be than it is better alternatives.
As example, bmpdj-bin have a terrific GUI, but it accept only the mp3 format and have becomed closed sources, when mixxx is very advanced too, is open sources and accept audio file formats like wav and flac.
Best and see You in the street, Dominique