The invention includes digital logic devices with extremely skewed trip points and reset circuitry for rapidly propagating signal edges. The biasing circuit utilizes the nonlinear rectified current of a microwave diode or transistor for biasing the amplifying transistor self-adaptively. One communication subscriber uses the check character from the last data packet received by the other communication subscriber as start value for calculating the check character for a subsequent data packet which is to be sent to the other communication subscriber. The modification profile may be used to adapt an audio or video source for a specific type of audio or video playback or output device.