*regulator
It's not that regulators degrade sound, it's that high current regulators get very expensive. Krell has attempted this, essentially an amp inside an amp, Sanders Magtech gets close. Class H amplifiers are, loosely, similar.
Everything is in the path, but not everything matters. As for power cables, I do like to use inexpensive but shielded cables to minimize the possibility of EMI/RFI noise being picked up after my power conditioner. My integrated includes a large ferrite bead around the incoming power line which in my mind will do far more than anything that can be done by a fuse.