What you can also try now that you have removed the ground, is to flip the plug back and forth (reverse the AC polarity) and see which way sounds better.
Lifted grounds- No more FM distortion on Tuner
I just realized that my FM reception is 100% perfect now. I recently got a pair of Rogue M120 Magnum Monoblocs and lifted their grounds. The Tuner and the pre is grounded. Prior to this upgrade the Tuner would have lousy FM reception and would get better in the late evening. Before the upgrade my integraded and all other components were grounded. Was I getting a ground loop which was affecting my Tuner reception? Why did this happen? What causes the ground loop?