Tested on a router, 12V. An incredible improvement compared to the Ifi iPowerX. All aspects of the sound are noticeably enhanced. I can now hear details in many places that I didn't even know existed. Dynamics have improved, and the soundstage has expanded.
I strongly advise everyone who hasn't tried a good power supply on their router to do so immediately. They can thank me later. The improvement is comparable to a much larger investment in another component. (Of course, this all makes sense if the rest of your system is on a higher level.)