Benchmark DAC2 HGC vs DAC3 HGC or??

Hi,

Can anyone detail the differences between these two DACs?   I've had a DAC2 for 10 years or so on my pc setup.   It drives powered Dynaudio speakers via Nordost Heimdal XLR cables/   The DAC is connected USB to my PC via a Audioquest Diamond cable.   I have always loved this setup as it transformed my workstation with respect to audio in every way.  I don't play studio cd's that much or stream.  Every now and then I play DSD files or a cd via the speakers or to my Eytomatic ER4/XR's 

I mainly use this audio setup for mastering music and live concerts with SoundForge.   I'm curious on differences in sound quality of the two Benchmark DACS and any other similar DAC that you like.

Thanks!!