Signal Processing:  What does this really mean and what is located in this section?  Well anything that alters the audio signal.  Everything from Dynamics Processors (Hardware compressors), Equalization (Hardware Equalizers), Conversion (A/D D/A Converters and Interfaces) and Multi-Effects Processors (Reverbs, Delays, etc...) and even Harmonic Boxes (I refer to them...Tape Saturation or Distortion) .  Anything that effects/alters or changes the signal is a signal processor