So i've had the Uber upgrade for nearly 2 months now, very happy with it. What made it sound its best was getting a good spdif cable. I was using a chincy radioshack digital coax for years, always under the impression that bits are bits. I decided to give the BJC digital coax a try after being really happy with their LC1 interconnects. and BOY did it make a big difference. My old cable must have had lots of interference or data smearing because my setup REALLY sounds amazing. There are no weird highs anymore (hard to describe.. they were super harsh coming out of my vintage RS1s) and the details increase 2 fold (maybe the lower noise floor is causing this?) and the separation, clarity, bass EVERYTHING just sounds incredibly better. However I didn't really notice a difference on some of my mid-fi headphones, only with the RS1 (my only real nice set of cans) and i couldn't ever go back to the rat-shack cable.
Just so you guys know what im listening to: x-fi xtreme music digital coax -> uber schiit bifost -> Mapletree Ear purist HD+ -> Vintage B Grado RS1
TL;DR if you are going the digital coax route, get a nice spdif cable (i recommend BJC) and it will really improve the sound. It did for me.