Hifial, there are many reasons why folks sometimes get no results or even results that hurt the sound with fuses or almost any audio device or component you can think of. While that is evidence there might be some issue with the fuse or device or component it is only one data point. All of the evidence must be assembled and plotted on a graph to build a case for whether the item under test is for real. Without such more complete evidence it is not a good idea to draw conclusions or make generalizations regrading the effectiveness of the thing since there are quite a few reasons why a person might not get the positive results he was perhaps looking for, including inserting the fuse in the wrong direction, to name one. To claim that everyone will obtain the same results is a little bit premature. Most audiophile fuse manufacturers have been been thoroughly vetted in the press and on audio forums, so there's actually little doubt about their effectiveness, generally speaking.
