VPI Classic hum

Got mine a few weeks ago. Installed it with a high-output Benz Ace H cartridge. Loved the sound but there was a hum when I turned the preamp volume past the 10 o'clock position. Later changed to a Clearaudio Concerto, the hum was quieter, but wouldn't go away no matter what I tried.

Then I read the manual closely, and it said something about using shielded interconnects. So I tried a pair of Rega Couple wires, which are made from Klotz cable, and are shielded.

And you know what, the hum just vanished! Now I'm at peace ...

Just to share with those have hum issues with the Classic. Do share your solutions.