GND methods for AT-120USB turntable

I have an Audio-Technica 120USB turntable, & have had it for the past year. There is some "hum" & occasionally more at other times. I recently switched from one of those 6Z5P+12AX7B Chinese 'Marantz 7' type preamps, which is another story; to an older NAD 1240. Much less turntable hum. I see these USB 5 pin breakouts on eBay, & wonder if an earth-ground could be created from such a device? Has anyone found a satisfactory way to GND a AT-120USB turntable?