A seredipitous benefit of the Smash

[Sonido]

I found something accidental about the Smash. In my analog vinyl chain, I have grounding 60Hz buzzing issues. Even with the grounding wire between the turntable (Pro-Ject Debut Carbon DC) and the phono preamp (iFi iPhono), while it reduces the amount of buzz compared to not using the grounding wire, there is still a noticeable buzz. However, oddly enough when I add the Smash into the chain the buzz is gone. Since I use very revealing headphones (HD800) instead of speakers with my vinyl setup, this is a big deal to my overall enjoyment. In fact, I've tried using the setup without the Smash and I can't stand the buzzing during the quiet parts. If I didn't have the Smash, I'd probably be trying all these different things to remove the buzz, though it's most likely electrical interference as my audio area is quite congested. But thanks to the Smash I don't need to bother with that!

So anyways, I wonder if anyone here more technically proficient in this area could explain how the Smash removes the grounding buzz?

[Doc B.]

Does one of your other pieces of gear have a two prong power cord? It could be that the Smash power cord is creating a better connection to your AC mains ground than you have without it in the system. Or, it is somehow breaking a ground loop that you have otherwise.

[Sonido]

Both the turntable and the phono preamp have only two prong adapters

[Grainger49]

If the two prong AC plugs are not phased you might try rotating them 180 degrees one at a time.  You could lower the noise floor even more. 

[Paul Birkeland]

Both the turntable and the phono preamp have only two prong adapters

The phono preamp with a two-prong adapter is most likely where your issue was emanating from.  If you run into the same issue in the future, a grounding wire from the ground post on the RIAA preamp to the metal chassis of your preamp ought to cut the noise out.