Hum with Gyro Dec/Lyra Helican/RB300 incognito

Can anyone help? I get hum when the volume on my preamp is 1/4 up from the Lyra Helicon. Is this normal, I have checked the grounding from the Lyra to the phono stage ( the Groove ), the connection of the ground reduces the hum a bit, but it is still there.
You might try floating the ground on the wall plug of your phono preamp.