Good notion about the regs. I always wonder about the longevity of equipment designed for 220 or 230VAC after years of use at the 240VAC we actually average here (when I lived near Selby - in line of sight of two large power stations - the mains voltage rarely dropped below 250VAC and would peak in the mid-260s at times: still mostly within the +6/-10% spec!).
The C-J manual has a LOT to say about EMI pickup - after denying that it affects the amp of course:
Electromagnetic Interference (EMI) Considerable care has been taken in the design of the CA200 to minimize its susceptibility to radio frequency interference and other forms of EMI. Choice of materials, physical layout, grounding practice, and power supply design have all been specified with a view to reducing the impact of electromagnetic fields on the performance of this unit. At the same time, however, our primary goal is the accurate reproduction of recorded music in the normal home environment, and we have elected not to compromise this objective by the application of heavy-handed RFI filters, or by using grounding practices that reduce RFI at the expense of degraded audio performance. We find that the approach we have taken has worked extremely well, resulting in only rare instances of EMI problems which could be treated locally as needed, rather than compromising the performance of our product in the 99.9% of installations where EMI is not a problem. Care in installation can often avoid EMI induced problems. The following practices should generally be observed in any application, and will be especially important where EMI may be a problem. Interconnect cables should be kept as short as possible (3 meters or less), and shielded cable should be used (cable which has two center conductors, and a separate external shield connected at only one end).
Physical location and cable “dress” can be an important factor in minimizing hum pickup. The installation should situate the CA200 well away from sources (CD player, tuner, etc.) and power (ac mains) cords should be dressed to remain at least 4" (100mm) away from input/output cables.
Could there be something like a server, wireless hub, etc nearby that's being picked-up? I presume the power stage has a LOT of gain given the line stage is passive, so could be a bit more vulnerable to pickup than is usual.
