You can use a 20a receptacle on a 15a line. You just can’t use a 20a powercord plug on a 15a line / 20a receptacle, otherwise you will have an ISSUE! Only use 15a powercords.
Replacing generic RECEPTACLES
How important is it to replace your generic receptacles with audio grade receptacles . I already replaced my stock power cords to high end Shunyatas. Would it still be necessary to still change my generic receptacles to audio grade?