Electrical question

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?  

Have the electrician put the audio equipment on the opposite phase from the microwave , if you get a funny look from them get another electrician