With a big honking transformer power supply, I would just plug it in. Toss a ferrite on the power cord if it makes you feel good. I have a whole house suppressor which if you can do, is highly recommended. If not, I would look at the amp schematic and see if they properly did any surge and RF internally. It amazes me how any product above the price-spec only market fails to do proper AC input design.
If you have a toroid transformer, a DC blocker is a good idea. Nothing wrong with a reputable power strip with RF filtering and surge suppression. I have used Iso-Max, Trip-Lite and Monster strips. Reputable, actual engineering.
None of that is going to make it sound any better. Just safer. I have not lost any audio to surges, but two stove control boards, two TVs and one computer. My audio is all old school with transformer inputs except my new DACs