Your out of luck trying to replace the main power fuse on the Marantz SA11-S1 as it is hardwired into the unit. But you can try a WA Quantum chip ($6.00 ) placed on the fuse or try the Synergistic Research Electronic Circuit Transducers ( ECT ) places next to the fuse. My Marantz unit has the WA chip and seven of the Synergistic Research ECT's inside. I did replace the five rail fuses with the Synergistic Research Black fuses. 1.6 amp, small, slow blow. Each fuse location did make a sonic difference but I did not try to establish which location made the greatest difference.
This unit really sounds good after these upgrades and they are removable if you sell the unit.
David Pritchard