Electrical question

You may get better sound with a dedicated AC line for your audio system, or at least separated from high current drawing appliances such as a microwave.  But I don’t think the lower voltage or limited current would damage your equipment.

There maybe be some equipment that suffer from under-voltage situations, but thst means far less than 112.  

More troublesome are things with motors that frequently and randomly come on and off, i.e. refrigerator’s compressor, furnace’s fan, lights on/off, all making unsteady supply and noise on the line.

One thing you can do is use a unit like the Furman PFR 1800

https://furmanpower.com/products/p-1800-pfr?srsltid=AfmBOorgkUijQxvj1W3EA1RrrglykQvVOmOOQ8ny0fQJZLceBtKRYDO6

You need dedicated line. The lower voltage won't hurt things b ut the sudden surge when microwave turns off could harm things in long run. 

The electrical code only requires a dedicated appliance circuit if the appliance draws more than 50% of the circuits capacity.  120 x 20 equals 2400 watts.  They microwave ovens draw is what is on the name plate not “cooking watts”.  Most counter microwave ovens do not need a separate circuit by code.  
   Is the house you live in built after 1980?