ground wire?

I have an older Thorens TD 165 turntable with a Dynavector 10x5 cartridge. There is no ground wire from the unit that would attach to the phono ground on my integrated amp. Is this a problem? Should I attach a wire to the metal chassis on the Thorens to the amp phono ground?
When you attach your RCA's to the amp does it hum? If not your don't need a ground wire.
There is no hum. So I assume I do not need one.