A sensor signal conditioning circuit of a machinery health monitoring module is disposed between a machine sensor and an analog-to-digital converter (ADC). The circuit includes a sensor interface connector, first and second operational amplifiers, a Nyquist filter, and first and second gain flattening feedback networks. The interface connector can connect to multiple types of sensors for monitoring various machine characteristics. The output of the first operational amplifier is coupled to the positive input of the ADC, and the output of the second operational amplifier is coupled to the negative input of the ADC. The first operational amplifier provides a high impedance differential interface to the analog sensor signal and a low impedance interface to the positive input of the ADC. The second operational amplifier provides an inverted copy of a signal at the positive input of the ADC and a low impedance interface to the negative input of the ADC.