double post
Thanks for the explanation. I live in New York City. We lose power, city-wide, infrequently, once in the last eighteen years Iāve lived there. Our lines are underground so they are not as susceptible to damage from thunderstorms as suburban areas.
There are local brownouts, in small areas of a neighborhood, so Iāll have to see if that happens where I live now.
I donāt know the odds of sustaining a lightning strike in a one hundred unit apartment building. Should I worry about that? I unplug my gear when storms rolls in but, of course, Iām not always home.
Iām probably not going to go to the expense of putting in a transformer to run my gear. I have two 20amp circuits, on the same phase, dedicated to the audio gear. My Gryphon Colosseum has its own dedicated 20amp circuit.
Overall, I think my system is very quiet. New York is not a quiet place so there is a certain amount of noise I canāt get rid of unless I put in a set of windows inside of the existing windows.
Leave alone and enjoy!
Note: Ground as zero voltage is theoretical. Only a conductor with zero impedance will have zero voltage, so in reality you will usually see varying voltages at negligible levels.
Thatās a very sensible conclusion 
Having their own dedicated circuits is the way to go. Large buildings usually have communal lightning protection.
Iām not sure what is common in US and having brownouts so infrequently you seem to be well covered.
Surge protection might be an option if required at a later date.
This reminds me of A story recently that happened near me: http://www.bournemouthecho.co.uk/news/15611962.Electricity_back_on_for__vast_majority__of_Boscombe_residents_after_major_power_outage_on_Friday/
Itās when they turn the power on that it can cause things to blow up!
Absolutely, this is where audiophile syndrome starts to take hold.
Protecting your gear is the most important thing 
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A voltage test between neutral and ground is not a way to test how good a ground is. A Google search will yield the proper techniques. If insufficient grounding is found, the best way of getting better ground is to increase the surface area of the grounding electrode which has contact with the earth (installing additional ground rods may be necessary). Of course the pathway for the ground to follow needs to be as freeflowing as possible.
And it is typical for there to be 0.5V (and up to 3V) measured between ground and neutral in a 120V system. It doesnāt mean that there is a problem such as a bad ground or leakage. Thatās just the natural relationship between the components of an electrical circuit.
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