The V Link brought the XDA-1 to the next level. Music sounded much more relaxed and I could listen for many hours at a time. Bass was good, mids and highs were smooth. I recently moved up to the Wyred4Sound DAC1 and using in conjunction with the V Link, the sound is much fuller, bass goes much deeper. Highs are very pure, no hint of grain. By comparison, the XDA-1 sounded a bit lighter. Even though my new dac has the 24/96 usb input, I prefer the sound with the V Link in the equation. It also enables me to listen to 88.2KHZ files as well.
I also foiund that digital cables made a big difference, I settled on Wireworld Starlight usb and spdif.
Bob