A subscriber line interface circuit contains a high voltage analog section, and a low voltage and digital signal processing section, that monitors and controls the high voltage analog section. The high voltage analog section includes a dual mode tip/ring amplifier unit coupled to a subscriber loop pair, and an input signal receiving unit, that conditions input voice and low voltage signaling and ringing signals from the mixed signal section. Attributes of and/or enhancements to the high voltage section are used to improve the operational performance of the subscriber line interface circuit, in particular, low noise, low power, wide-bandwidth and wide dynamic range characteristics.