Class D Technology

bcgator and mapman I am with you guys all the way. I had the GT200 mono block tube amps from Tube Research Labs. They were by far the best tube amps I have ever heard. Does that make me an authority? Absolutely not. But when I replaced them with H2O 250 SE mono blocks my world was turned up side down. Were the 250s as warm in the mids? No! But guess what.I used a tube pre-amp (the TRL Dude) the Ayon Skylla 2 DAC and I was 90% there in the mids. What I did NOT have was distortions (even order nor odd order) that was obviously missing since replacing the tube amps. I have the Sound Lab A3 PX speakers and as you say " full range" with a vengeance. Unfortunately components add their own color. That is the nature of the beast. So system matching is always the challenge. Just bringing the Sound Labs 4 inches closer to each other dialed the sound right in. I hear the arguments and look at the measurements  and guess what the sound contradicts those arguments and measurements. Not one of my audiophile friends has not been floored with the sound. They too have heard the class A tube monos and said these thing eats them for lunch. I think it was you Mapman that said you changed a cable. There you go, system matching. If you are ever in Columbus, Ohio stop in for a listen.

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.