In Pro Tools, which capability is provided by the use of Aux Input tracks?

The use of Aux Input tracks in Pro Tools primarily serves the function of effect routing without altering the original track. This allows users to apply effects or processing to multiple audio signals simultaneously while keeping the original tracks intact. By routing audio from various tracks to an Aux Input track, users can manipulate the audio with effects such as reverb, compression, or EQ, and the changes will be applied to the signal being sent to the Aux track instead of directly affecting the original audio tracks. This enhances flexibility and non-destructive editing, which is especially useful in mixing environments, allowing for adjustments without committing to changes in the source tracks.