I bought my DFB with Jitterbug in a value combo, so I hardly use it without. I don’t have a media player, just an iPhone6. I think I hear a difference with camera adapter 3 when charging, improved with jitterbug, but I have not done testing. @Torq was going to post something about a year ago regarding jitterbug, but if he did, I missed it.
With one exception, which involved perhaps the worst computer I’ve ever had the misfortune to be saddled with (a loaded Dell 7600-series workstation, fortunately not something I had to use outside “work”), I’ve not found any audible benefit to the Jitterbug.
The testing I did showed effects if I measured the actual USB lines directly … but these were so small as to be essentially meaningless. And none of my measurements showed any differences at the analog output of the DAC being fed.
Which is pretty much the same story for every USB cleaner/filter/re-clocker I’ve ever tested (DDCs are a different matter). Even chains of them. And in some cases, they’d either make things worse or even stop the USB device working entirely.
Only other exceptions were units that were essentially powered hubs, with maybe a single output port, and then that was really about addressing unreliable USB operation in the first place with some borderline laptops.
Placebo effect. Back in the early days of car radar detectors, one could by a miracle plastic box with lights on the outside. The device had no functional value, but not all buyers returned them. So, the seller made a net profit after the returns. This is the evil version of capitalism, and one reason I’m leery of ifi, AudioQuest and a legion of other audio vendors.
LOL I had a string of Dells for work and that’s just what I was thinking of, the audio was terrible, whining noise in my headphones every time the hard drive spun up.