Where has been your most effective placement for an aftermarket fuse?

Not looking for a debate with anybody on whether aftermarket fuses work or not, this thread is for those fortunate members with the hearing to know that they do indeed work.
I am very interested in your thoughts and opinions as to where they work the best, the biggest bang for your buck if you like.
For myself I am going to say it is in my Metrum Onyx DAC.
And not just my present DAC, all of my last 3 DAC,s showed a very nice easily audible improvement with an aftermarket fuse.
Next I would say is in my Gold Note phono stage and lastly in my BAT integrated amp.

So what or where would you say has been the most noticeable piece of equipment that has benefited from a fuse change in your system?