Albert Porter sells cryoed outlets that are a major improvement over the home-standard variety; and they are moderately priced.
As to covers, I Home Depot's reasonably-priced solid brass outlet plates make a noticeable improvement in sound although I don't know why they work.
As to covers, I Home Depot's reasonably-priced solid brass outlet plates make a noticeable improvement in sound although I don't know why they work.