Santiago, Chile

I just bought a Wadia 781iSE CD player and trying in DIRECT mode with my amplifier it produce a ground hum. It wasn,t only with my unit because other friend with the same Cd player have the same problem. I tryed with different interconnect cables thinking it was a jitter problem and the hum remain.After brake my head looking for what was the problem, I decide to disconnect the ground wire from the power plug and the hum dessapears. Does anybody deal with the same trouble ??
I present the problem to Wadia post selling service but they haven´t answer at all.