Whole house surge protector - did it, big YES (so many appliances and electronics, big and small, that need protection)
Dedicated audio curcuit(s) - did it, big YES (did three, one per receptacle, certainly a luxury for my small/simple audio system)
Cryo'd hospital grade 20 amp duplex convenience receptacles - did it, big YES (the only part of all this that we paid, $100 from cryoparts for Hubbells, for as it was bid lump sum)
Wired a separate ground to connect all audio circuits together - did it, big YES
Wire the entire house with 12 gauge wire and 20 amp breakers - did it, big YES (some new appliances, like our washing machine come to find out, requires a 20 amp receptacle/circuit)
Underground feed with your own transformer - did it, big YES
Wire in a plug in and at the panel for portable generator - did it, yes
Wire the audio circuit(s) to the top of the panel - missed that one, but some recommend it
All this said, IME "clean" power, properly termed a lack of abberations, is location specific. Age/condition of wiring, substation, even power plant are all contributing factors. Number/age of industrial and other heavy users can easily be heard. Thankfully I've not had many of these factors where we live, and now am in good shape on these counts.
Most of all the posted advice is in the "while you're at it" category. And it you're situation, a little forethought can pay mighty dividends.