thanks for the clarification mneary and crutschow.
as for the audiophile bashing, I am well aware of the hocus pocus that goes on. however I am not talking about thousand-dollar filtered power cables. I am talking about a ten cent capacitor and a ten cent resistor. the schematic I posted was a simple rectifier and reservoir cap power supply. snubbers are used in other areas of electronic design, it would make sense to at least try them on an audio power supply to suppress transients. it might not work to improve sound but its under a dollar of parts. and yes the guy talks about sparkling highs and magical mids on his webpage, so I take it with a grain of salt. I can't hear above15kHz anyway.
the schematic provided was meant as an example of a snubber being used. I meant my question in a general sense - i suppose it would depend on the specific transients in my hypothetical system, but if I were getting unwanted spikes in a circuit like that (psu capable of say 200W, powered from wall), what sort of spikes might I expect, and what's a good rule of thumb for rating snubber parts appropriately? try and look at the spike with a scope, estimate the average power in one transient, and based on the duration and frequency of occurrence of the transient pick a resistor and cap that can handle it?