The diagram below is a simplified representation of the signal flow through the miniDSP Flex (without Dirac Live):
The audio signal in the diagram flows from left to right:
One of the five stereo input sources is selected by the user.
The selected stereo input signal is passed through the input channel processing blocks: level metering, input gain, and parametric EQ.
The processed input channels are fed into a 2-in 4-out routing matrix that routes/mixes the two processed input channels to the four output channels.
Each output channel runs a comprehensive set of DSP functions: parametric EQ, crossovers, FIR filtering, level metering, delay, output gain and compressor.
The combination of the routing matrix and the crossover blocks on the output channels is what gives the miniDSP Flex the ability to be used in many different system configurations.