A signal transfer and processing system for use with a transmission line includes transmission line interface circuitry (30) and signal processing circuitry (100). The processing circuitry receives a signal to be processed, providing a processed signal for further use. An input bandpass filter (119, SW7) selectively limits bandwidth the input signal. A primary active frequency control (123) selectively controls the relative level of the signal provided from the primary bandpass filter means for selectively controlling the relative level of signal dynamics within different frequency bands for providing a frequency controlled signal, which is compressed by a compressor (127). A secondary active frequency control (135) selectively controls the relative level of the primarily compressed signal within different frequency bands to provide a frequency controlled primarily compressed signal which is further compressed by a secondary compressor (137). A feedback circuit (128, 129, 140) between the primary and secondary compressors limits compression by the primary compressor as a time-delayed function of level increase of the secondarily compressed signal. An output bandpass filter (152, SW8) limits bandwidth of the secondarily compressed signal. Switching circuits (30) interconnect signal input and signal output of the signal processing circuitry with the transmission line for causing signals transmitted by the transmission line to be automatically directed through the signal processing circuitry.