Could you please check a few additional points?
- When the volume does not increase or decrease even when you turn the volume knob on your RS451, please check whether the Pre-Out Level is set to a fixed level. If a fixed output level is enabled, the volume knob will not adjust the volume.
- For the video files, you can upload them to your Google Drive and send us the shared link. This will allow us to review the videos even if the files are too large to send by email.
Additionally, if you experience the volume control issue again, please go to Input/Output Settings ā Output, tap the small gear icon, and check whether the Pre-Out Level setting is enabled or set to a fixed level.
Thank you.