I agree that they are an improvement (slight but noticeable) in sound over standard wall outlets. But unfortunately they do not have a strong enough grip on heavier gauge power cables. I have been using two for the past couple years and must hang my plugs that go into the porter ports with heavy rubber bands hung over a screw in the wall above them. I also have two PS Audio power ports. No issue with grip on them as they as super tight fitting. And I can tell no difference in sound between them. So if you are thinking about buying the Porter ports and are using heavier power cables like my Pangeas 9SE, be prepared to provide additional support for them due to their rather sloppy grip.
MRI grade vs Hospital grade electric outlets
I know both have been suggested as an upgrade to the run of the mill cheap outlets. I also know there may be "even better" outlets. I know the MRI grade has non magnetic metal components. Bottom line, does it make a difference one can hear? I have about 1/2 dozen Hubbell 30 Watt hospital grade outlets. Got them fairly inexpensively. Are the MRI grade worth the extra $$$?