Those are fairly typical types of differences I hear when comparing good physical transport to PC audio.
If one cannot give up the convenience of PC audio, then streamlining the PC audio signal chain will narrow the gap. Qutest owners are lucky because the thing is so darn small and can be positioned in such a way to get rid of at least two cables, USB cable and BNC cable, which makes a sizable difference.
I’ve got PC/SoTM USB card->DXIO USB-BNC converter->Qutest without a single USB cable or spdif cable, connected back-to-back with USB adapter and RCA/BNC adapter.
0113201945_HDR by drjlo2, on Flickr