The upgrade to the 3.7 caused immediate improvement, but I am not certain how to describe it. There
certainly is more detail, especially noticeable in the mid-range and top
end. It also sounds better tonally, and sounds both more detailed and
denser at the same time. There are lyrics in one song, the acoustic version of Rooster by Alice
in Chains, I understood for the first
time. Johnny Cash singing Hurt is as good as I have heard it. (A cover
of Nine Inch Nails.) I am running this DAC with Bel Canto's REF600M amps.