To reduce the buzz you sort of need to know what is producing it. Is it definitely coming from using the microphone into the VS-1680 and if so, have you tried a new XLR to XLR cable?
- If you have another microphone, such as a dynamic is the buzz still there?
- Do you have any devices nearby that might produce electrical noise, such as CFL/florescent lamps?
- Does moving the microphone or cables around change the sound of the buzz?
- Are there other devices plugged into an input of the VS-1680 that may be powered from an AC outlet? Preamp, keyboard, etc?
- Can you post a short clip of the buzz?