OP…I think by now it’s clear that fuses will not solve your bright system issues.
I also don’t think that breaking these cables in will completely eliminate this brightness.
Few things to resolve this -
1. All silver cables not a great idea. Try pure copper speaker cables first then go up the audio chain to replace the interconnects feeding the amp first.
2. Room acoustics. Thick rug, treating first reflections if possible
Address the items in the signal path first if room acoustics is not feasible to tackle.