I found the QX-5/20 to be a game changer in my system even before the update,
I did buy it used rather than waiting for a QX-8 (my original choice) as I was hoping to stay around 5-6K. Once is saw the used Qx-5/20, I just bought it.
My dealer carried DCS and Boulder so I heard some very high end DACs over the years but at that time my main source was an ML390S and I was not thinking about streaming. The Boulder was amazing but everything in that demo chain was at the top of their line..
I have to admit I am partial to the Ayre "house" sound" so my opinion in slightly tipped. In fact, soon after I settled in with the DAC, I update my preamp to a KX-5/20 from an ML 380S.
Wish I could help you more. Jerry