Caelin Gabriel and Shunyata make suppressors for medical gear so I think they're a lot more knowledgeable than most people here.
Than most people here is not setting a very high bar but even then I am not sure. They say a lot of dumb stuff.
150 vrms. They use 140v MOV probably. Not doing anything till 240 DC. A big surge is going to be over 400V. The datasheets don't give a lot of details.
What's the controversy? Whole house plus a power bar for surge protection. Seems pretty obvious. MOVs don't do anything to your audio. Crazy to believe they do.