OP, in the SR fuse packing it clearly states to insert the fuse from the S to the R. Or left to right.
The first thing to do before you take the hood off is power off and un plug the power cable from the back of the preamplifier/amplifier.
Only insert one fuse at a time and the first fuse should be closest to the IEC inlet and the power train.
Insert the fuse, plug in the power cord and power on, after some period of time you will be able to tell by listening if the fuse is in the right direction. Since these fuses are directional they will sound strident if they are in the wrong direction. If so, power off and un plug the power cord and simply reverse direction.
All the above applies to both your preamplifier and amplifier and my experience with the SR Purple fuses.
And please, don’t listen to the naysayers. It’s your rig and your money. Besides I’ve learned that the monitors here on Agon don’t mind and possibly prefer some spirited debate.
Especially with the so called know it all testers. You know the ones, that only believes something if and only if it’s measured some sort of way. There is nothing wrong with using your ears. Everything is not new audio part bias. As if.
These are the same electrical engineers who don’t believe in cryo treating metals works either even though the aeronautical (engineering) industry and others have been using these techniques since the 30’s, all the way down to the of tiniest parts molecular level to some of the most massive parts for rockets and jet engines.
You will find that in some fuse positions there may be no effect at all. That is one of the reasons to test each SR fuse at each separate position one at at time using only one SR fuse at a time with the original fuses. Is it time consuming? Yes. But you will find that in certain fuse positions no new or SR fuses are needed. As the original fuse is fine where it is. But that comes from a lot of trial and listening.
And the ones you find you don't need, send them back for a refund before the 30 days are up. Just so you know, there is a buy two get one free sale on SR fuses for the month of April/2022 and they can be mix/matched too.