Class D Technology

My advice for anyone on the fence is do your homework, listen and decide for yourself.   Only then will you know.

   I'm no scientist but I understand the difference between theoretical noise and actual verifiable noise and that, empirically, only the actual noise can actually be heard. by us humans.  Noise needs to be heard to exist.  

Class D amps are nearly immune to any noise they (or their SMPS) might make. The switching occurs at the output of the amp to which speaker cables are attached, which might make a suitable antenna.

Its the other gear in the system that is really the concern (not to mention pacemakers and the like in the area)- they might pick up the radiated RF noise and might react poorly to it.

However, neither of these are really issues with any competently designed amp or power supply, and while I get the concern, its mostly a red herring. You would never be able to ship an amplifier (or power supply) out of the country if it made any appreciable noise!

So I don't think this is anything to be worried about.

I am extremely happy with my Theta Prometheus amplifiers. The front end tubed preamp just makes the result that much better. If possible listen to the amps in your system.

I've observed part of the maturing  of Class D technology in recent years is that noise as Atmasphere mentions is a valid concern that may have been a more common issue earlier on in some cases when not handled properly but should not be and is not in practice an issue normally anymore with newer well designed and properly functioning Class D amps.

Speaker cables would be a very poor antenna.  Since wavelength of 500kHz switching frequency is 600m a typical 2m cables would be 1/300 wavelength antenna.  Usually antenna becomes rapidly ineffective below 1/10 of the wavelength.