Open source hardware digital signal processing platform from Paul Janicki:
The open hardware DSP platform is a range of small boards that can be plugged together to give you a flexible platform for processing all sorts of audio signals. If you want a simple crossover, a custom USB soundcard and headphone amp, or a fully fledged 48 channel mixer or synthesizer there should, eventually, be something here to do it. All board designs and information are released under the TAPR Open Hardware License.
Current board designs include a digital signal processor, 16 channel digital to analogue converter and single ended output stage, power supply, and single ended and balanced stereo analogue to digital converters. All released designs are hosted on GitHub.
Full details at Paul Janicki’s blog.