Either the outlets need more time to break in, or you don't like their sound. You will have to wait and see which of these is the case.
This assumes that other things are not responsible for the problem, such as:
Equipment being off for extended time while repairs to electrical were being done.
Equipment suffered a failure or alteration in set up when taken out of service.
You altered the electrical service when the electrician changed the plug, reversed polarity, used new material not broken in, or pulled the power from a different breaker than before and there is a problem with (noise?) or something on that circuit.
If none of this has occurred, your just going to have to put some hours on the outlets before deciding what they are doing.
This assumes that other things are not responsible for the problem, such as:
Equipment being off for extended time while repairs to electrical were being done.
Equipment suffered a failure or alteration in set up when taken out of service.
You altered the electrical service when the electrician changed the plug, reversed polarity, used new material not broken in, or pulled the power from a different breaker than before and there is a problem with (noise?) or something on that circuit.
If none of this has occurred, your just going to have to put some hours on the outlets before deciding what they are doing.