These guys have found another solution to what should be an inaudible problem in competently designed gear, Franks home theater in a box where he can hear these things (high noise and hiss and what not) does not make them problems in competently designed systems. While there are ground currents, there are noise voltages all over your cabinets and coming from a resistor just setting there and everything else, is it an audible problem in your system? In fact, for many of us tube lovers, a slight bit of noise is NOT a problem at all. Same with tape, that noise dither may smooth out some of the higher harmonics that we don't like to hear.
I have a ultra cheap ($20.00)Lepai class T amp, it powers some ultra cheap (pioneer SP-BS22-LR $130.00) speakers, with my lap top as the source via a three feet fairly cheap cable. When I unplug the cable from my laptop, and turn the Lepai all the way up, I hear no noise from the speakers at my listening position (which is near field). If I plug that cable into the computer out jack, and turn the Lepai volume all the way up, yeah I hear some (lots really) noise. But I don't experience that with my main system, I don't hear any noise at my listening position with 440 watts per channel and my entire audio chain connected. So, yes, while it is measurable and there, if you cant hear it, IT, is not a problem IMO.