Why is a 1.5-2 volt AC signal on my Neutral line?

I gave a complex answer. Here are a few simple solutions.

If the NAIM has an optical in then try that.

Disconnect the video to the TV and see if the hum goes away - if it does then check your TV is grounded properly (no cheater plug).

Whatever you do - do NOT use cheater plugs on the Naim or on the TV - this can expose you to dangerous voltages in the event of an equipment failure.

Shadorne

Whatever you do - do NOT use cheater plugs on the Naim or on the TV - this can expose you to dangerous voltages in the event of an equipment failure.

I don't recommend using them as a long term solution, but they're perfectly fine for troubleshooting.

You also need to measure the RCA neutral to the case of the
equipment for voltage difference.If it there,that could be inductive pickup from the case housing the transformer, especially in a power amp with a big transformer.If the difference is between the neutral and ground at the outlet, that just may be the load on the feeder causing a voltage difference.This may be normal when there is a load
on it.Like mentioned above,clarification is needed.The power bar may be all metal,and tied to the outlet ground.
I go with the more clarification needed also.

Thanks all for the feedback - just to clarify the situation

The house is 23 years old and the supply comes in from the street via a subterranean cable.

The breaker box is earthed to the water supply pipe - and I could not detect any grounding problems at the breaker box or anywhere else in the house - I have verified there are no spurious voltages between neutral and ground anywhere in the house (tested with a very good digital meter for resistance, continuity, AC and DC Voltage) - particularly at the outlets with appliance connected - BTW all appliances are new this year - so no old lunkers are causing problems.

I also tested the equipment with only the dedicated line to the hi-fi turned on - YES - I took all of the other breakers offline.

Each piece of equipment (has a two pin polarized plug) was tested without connecting it to the amp and found that Sony, Panasonic, Pioneer and Toshiba all had a 1.5-2.0v AC voltage between neutral of each phono socket (and also the chassis) and the ground of the outlet they were plugged into - I also verified that the outlet did not have any spurious voltage present before plugging in the equipment - However on testing the Cambridge Audio sources and the Luxman sources I found they did not produce any voltage between their phono neutral or chassis - so they work well with the amp.

I have spoken to NAIM tech support and they indicated that their design philosophy is somewhat different from that of the consumer electronics manufacturers and that difference results in a hum when used with them.

Their solution is to use a ground loop isolation device which are commonly available, between the amp and DVD player.

I would guess that other hi-fi oriented manufacturers adopt a different design philosophy that allows consumer electronics to be connected without a problem, because I have not found too much on this topic - other than the normal ground loop problems due to bad cabling/mains/ground etc...

other than the normal ground loop problems due to bad cabling/mains/ground etc...

Yep other than the normal problems from using RCA.

Please understand that stray voltages ALWAYS exist but for the majority of cases the micro-currents are small enough so that they do not induce much audible hum as they circulate through your interconnects. The only proper solution is balanced - invented ages ago - but the desire by manufacturers to reduce cost means you often get RCA - even on expensive components.