PB, If I use the anti-phase diode approach, can I connect the audio ground to the chassis at the line end or should it also be grounded from the load end, like the shields? What would yield the best result? I'm concerned that, just like the shields, there is a possibility of picking up noise from the AC input, even with the diodes in place. Connecting at the line end is easier, mechanically, but it's worth the extra work to do it from the load side if I am running the risk of greater noise pickup.
Jamie