Probably a variety of things.
Again, look at the Audio Science Reviews for these things. They have the best measurements on what is actually working and not.
Also, I used the Wyred4Sound Remedy and found it quite effective with older DACs, but it wasn’t USB. New DACs didn’t care.
Regardless, none of the anti-jitter products I am aware of are intended for use between a memory stick and a streamer. There's a lot more that the streamer has to do than read audio data. You want to have the jitter taken out afterwards.
In the old days, USB ground loop isolation was not common, and made a difference especially with laptop power supplies. Now I rather expect all decent DACs to have this.
And as ASR and the recent Stereophile review shows, those devices are nearly worthless with top tier modern DACs.