Available as an assembled Module and as a DIY project.
This Module is currently available.
4-channel mixer/attenuator with 2.0x gain and 5V offset
http://ljunggrenaudio.com/products/Mixers.html
https://synthcube.com
6 Users are observing this
These merchants probably sell this module. Huh?
Included in 964 Racks, 559 are public: