SR Fuse Orientation MW Sony 5400

I don't know about the SR Black, but the SR Red and SR20 are both directional based on the direction of the printed name on the fuse.  So, if the print on the fuse is from left-to-right, that is the preferred direction of current coming in from the A/C.  As far as positioning in the Sony 5400, it looks like there are 2 fuses on the power supply board.  You might have to take a multimeter and figure out which fuse is connected directly to one of the contacts on the IEC socket.  Sometimes the two fuses will be in serial, which means that one fuse follows the other inline.  You'll be able to tell with a multimeter howe the fuse contacts are connects (make sure you measure this with the fuses removed).  Sometimes there are elements in the circuit between the IEC and the actual fuses and you won't be able to tell A/C current direction.  In this case, you'll have experiment on directionality.

"I don't know about the SR Black, but the SR Red and SR20 are both directional based on the direction of the printed name on the fuse. So, if the print on the fuse is from left-to-right, that is the preferred direction of current coming in from the A/C."

Is that true or is the printed name on the simply a way to keep track of the direction whilst one is trying the fuse both ways. The same way arrows on some other fuses are just indicators of which direction the fuse is currently in, not the direction the fuse should be in.

I have tested one RED fuse and also had about 5-10 different SR20 fuses in both small and large sizes.  They are all directional based on the printed letters.  Others in other forums have also commented on this.  You can experiment.  Sometimes people like the opposite direction better, but in my opinion that direction will lose midrange/midbass punch.  The sound might be a little airier but it will also sound weaker.