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If it uses a voltage control for volume as some of the modern integrated amps do, then it's possibly quite straightforward.
For a conventional amp with the audio going through the volume control there is no way of sensing the position, only audio level.
It would likely need significant modifications.
What is the amp and how is the volume control fitted? If by chance it's on flying leads a mod could be fairly simple, but for a PCB mounted control it would be more complex (unless it's a DC voltage type).
Or, do you mean just an audio level display rather than volume control position?
LM3916 bargraph driver can be used as the basis for an LED VU meter. Or an actual analogue meter, which could be marked "VU". Not sure where you'd connect it to the amp. Aux out via an attenuator is easiest if it's available, somewhere soon after the volume control internally if you want to be more technical. Across the speaker is also possible but again you will need an attenuator.
What kind of information do you mean?