I have imported several class D modules from China and all but one have had RFI problems and seemed to me to unusable and probably illegal in a production item. Far to much RFI on the output and looking at the on board components they have only a single stage output filter comprising of a square grey ceramic choke and one or two mylar caps. Has anyone else found the same thing and is there a mod that is known to work? The modules are all very well made using good quality components but like behaving like a radio transmitter.