@westom
Please describe which power supply design you are talking about? I haven’t done an exhaustive study, but after examining say, two dozen devices, including DAC’s, mostly amplifiers and preamps, headphone amps, etc., I have yet to see a single one that included "robust" surge protection. I will occasionally see UL listed "noise" filters which are not the same thing, so I really would like to see what you are talking about. The one location where I have seen consistently and extensive use of surge protection is in PC power supplies.
Westom, you are also misinformed about the latest surge technology. Series mode does not connect to ground. They use a very large coil (compared to most surge protectors) instead which becomes the high voltage point in the circuit, and dissipate surge energy as heat instead of current. Their UL listing proves the effectiveness, and the normal "joule" rating becomes irrelevant.
A ground circuit is not needed in an SMP, so the quality of the ground for this application is no more needed than for GFCI circuits. As for your parallel devices being "harmless" we had about 2 dozen of these "harmless" protection devices (MOV’s?) in surge strips flame when a glitch in the local switching station occurred. They did protect the systems attached, but the speed of the surge was a lot slower than lightning.
But the cost / value item is another issue. I find the Furman devices inexpensive enough, and my gear precious enough to worry about it.
Best,
Erik