Nerspellsner, you do know that only the unbalanced load travels back on the service entrance neutral conductor to the source of a split phase secondary single phase transformer. Having all of your 120V motor loads on the opposite Line as your audio equipment is futile imo. A condensed example, if a 10 amp 120V load is connected from Line 1 to neutral and a 10 amp 120V load is connected from Line 2 to neutral, then 0 amps will travel back on the service neutral conductor back to the source, the utility transformer. The current from L1 is in series with the current from L2.http://www.ibiblio.org/obp/electricCircuits/AC/AC_10.html#xtocid269100
I have been playing with a 2KVA iso xfmr that only the CDP is connected to. What I have read on AA is when an iso xfmr is connected between a CDP and the main power line the xfmr serves two roles. It stops line RFI/EMI noise from intering the primary side of the CDP power transformer, and stops the noise created by the CDP from getting back out on the main house ac lines. Is all this true? Makes sense to me....
What I can tell you the CDP definitely has a lower noise floor, sounds smoother and fuller, just more analog sounding.
The CDP is an Arcam Alpha 9. The Alpha 9 uses a toroidal xfmr for its power supply. The xfrm itself was fairly noisey, mechanical hum, before I connected the CDP to the iso xfmr. You could hear the little sucker about two feet away when no source material was being played. With the CDP connected to the iso xfmr I have to put one ear up close to the side where the CDP's power xfmr is located. The guys over on AA say toroidal xfmrs mechanically hum excessively when DC is on the AC power line. That one I have trouble understanding but apparently it can be there.
At the present time I have the secondary of the iso wired as a straight 120V out with one output lead bonded to ground. Thus becoming the grounded conductor, the neutral.
I made sure the iso secondary polarity matched that of the main electrical house power Line that my preamp and power amp branch circuits are connected to. Jmo this is important being my preamp and power amp are connected to the house power through dedicated branch circuits.
So I guess what I am saying you could try an iso xfmr for the CDP. Size? "Zargon" an Agon member is using a Topaz 125va xfmr. Send him an email and ask him what effect is has on his system. Oh by the way he is first running a Topaz 4.2kva iso to feed all of his system and then plugging in the 125va Topaz to isolate the CDP from the rest of his system's AC power.