A summary of my design thus far (work very much in progress)
- 8 channels of digital audio (considering upgrade to 16 or more)
- Backplane with PCI-express connectors (cheap connector with many pins, saves cost on module)
- Daisy-chain modules to allow DSP of any input (or no DSP module at all)
- Module capability discovery via I2C/SPI EEPROM- Minimal work required of CPU (e.g. choice of Arduino, Raspberry Pi, maybe 6502 if you can bit-bang the bus)
Vague block diagram:
(signal flow is from left to right, my drawing tool was too tedious to add arrows)
Control module may or may not also act as an input module (signal source).