Amplification is a type of signal conditioning that improves accuracy in the resulting digitized signal by increasing signal amplitude relative to noise.
For the highest possible accuracy, amplify the signal so the maximum voltage swing equals the maximum input range of the ADC, or digitizer. Your system should amplify low-level signals at the measurement device located nearest the signal source, as shown in the following figure.
If you amplify the signal at the measurement device, the signal is measured and digitized with noise that may have entered the lead wires. However, if you amplify the signal close to the signal source with an SCXI module, noise has less impact on the measured signal.