Borrowed a very expensive USB cable this past week to try in my big rig at home. Source is a Mac Mini > Pure Music (Integer mode) > Ayre QB9. I had been using the cable that came with the QB9. As much as I hate to admit it was a huge step up in performance - much greater transparency that allowed much more musical nuance to come through. Using the expensive cable, playing Emmylou Harris's Boulder to Birmingham (Producer's Cut 24/96), her emotion comes thru in the music and hits hard. And the QB9 runs asynchronous transfer mode, so you wouldn't think USB cables should change the presentation.
Of course all good things must come to an end - cable has to be returned tomorrow. Took it out the system and put in the old. Decided to play Boulder to Birmingham one more time. All that sense of emotion was gone....
Before you flame. Went upstairs to talk to my wife who was in bed in another room. First thing she said: Something changed - the song didn't sound nearly as good the last time you played it. She didn't even know I had a borrowed USB cable in the system. Wasn't a DBT, but it certainly was a blind test....