Re: D-Fend
I already wrote about this when this was posted over on PSW(? maybe here too).
Simply stated it is a HF solid state chopper (kind of like a sophisticated light dimmer), so after filtering the amp output looks like less voltage to the speaker, and the speaker looks like a higher impedance load to the amp, so both ends are happy (even the tree huggers are happy because no watts were wasted other than the modest drive electronics draw).
One very tiny ding is that it parasitically steals power from the amp output signal, but if properly done this should not cause audible distortion.
The pro is that this allows you to idiot proof (customer proof) passive speakers which is surely attractive for premium speaker makers. The con is it will add cost that may keep it from being used in the lower priced gear, that probably needs it the most. Near universal use, could drive some economy of scale, but these are redundant for powered speakers and well managed systems with easy access to amp gain, so I am not that optimistic about these becoming ubiquitous everywhere. It is patented so somebody is probably hoping for that, and I wish them luck.
I give it one thumb up (for cleverness), but my boring by now advocacy of smart powered speakers makes this superfluous. I see a niche with premium passive speaker sellers, and if the price is right this could find a home lower down the food chain where the volume is, but I know how viciously sharp pencil the value segments are.
JR