Hi Dave,
To answer your questions clearly, I should probably first state that 60 Hz AC power" consists of a vast number of different frequency components. The highest amplitude/biggest of them is the 60 Hz component, of course. But there are also components at much higher frequencies corresponding to the brief high current spikes you mentioned earlier, probably extending up to tens of kHz, particularly in the case of power amplifiers. And there are frequency components at integral multiples of 60 Hz (i.e., 120 Hz, 180 Hz, 240 Hz, etc.) corresponding to harmonic distortion that will be present in the waveform to some degree. And there are essentially an infinite number of low level frequency components corresponding to noise, extending up into the RF region.
In answer to your questions, yes, strictly speaking a resistance at any frequency other than zero Hz (i.e., DC) should be referred to as impedance, which reflects a combination of resistance, inductance, and capacitance. And, yes, resistance in series will add to impedance.
In a local (in-house) power distribution system, however, impedance at 60 Hz will be dominated by resistance. Inductance and capacitance will become more significant at the frequencies of the much higher frequency components of the AC waveform. But I would not expect the inductance and capacitance of an outlet to have a great deal of significance in relation to the inductance and capacitance of the power cords and the house wiring. Everything else being equal, the inductance, capacitance, and resistance of conductors are proportional to length (although of course everything else is rarely precisely equal).
In answer to your last question, the impedance of the power delivery system should be low, at least at frequencies up to and somewhat beyond the frequency components corresponding to the brief high current spikes that have been mentioned. (Series impedance that is high at frequencies greater than that may be helpful in reducing noise, but I would not expect an outlet to play much of a role in that regard).
**HOWEVER**, for any design parameter that should be low there exists a point beyond which further minimization will:
1)Be overkill, that increases cost but accomplishes nothing, and/or
2)Be negligible in relation to the contributions of other things in the path that also contribute to the parameter, and/or
3)Be accomplished at the expense of other parameters that may be significant.
The basic point to my previous post was to provide a quantitative perspective on the differences in resistance that were cited in the reference you provided. Consistent with my comments above and in that post, I believe that if in fact there are differences in the behavior of those outlets that are audibly perceptible to some listeners in some systems, the differences in resistance that were indicated in the reference are very unlikely to be the reason. And even if there is a difference and resistance is the reason, the difference could work in either direction (good or bad), depending on the happenstance of the line voltage at the particular location and on the design of the particular components.
Regarding your mention of matching of metallurgy, that is outside of my areas of expertise and I have no particular comments.
Regards,
-- Al
