I don't think that is good enough. You really should demand the power company run a dedicated line for you straight back the power station. :R
Well, actually the transformer outside your house provides the low output impedance that is required to do a proper job of supplying ample current. The problem is that you have quite a few feet of electrical wire from the pole, through the service panel, and through the walls until you get to the wall socket that your equipment is plugged into. This in-line impedance can actually be lowered with a proper transformer local at your equipment, but the cost can be quite high (something like the Bryston Torus
units or similar are quite good). It has to be a large low output impedance transformer that will be able to provide a lot of instantaneous current.
Even replacing the rather limp 99 cent wall receptacles that most people use at their equipment can help quite a bit in lowering the impedance to your equipment. Or, installing dedicated lines are a big help by reducing the number of connections used in regular circuits.
As far as the effect of after market power cords - forget it.