Upgrade DAC recommendation

My 2 cents, check out the Sonnet Morpheus DAC.
Excellent DAC and well under your price cap.

concur that sonnet/metrum and denafrips (among others) are excellent

Based on the components in your system the Node is the weak link imo.
+1 on the Sonnet Morpheus.
I have done A/B comparisons with my Metrum Acoustics Pavane and they are close but the Morpheus has a more focused sound stage especially the center imaging and it has a little more weight to the sound.
Cees uses 16 DACs on 4 boards with FPGA on each as opposed to 8 DACs on 8 transient modules. The Morpheus is a continuation of his R2R design but it's in a less expensive case to bring the cost way down compared to the Pavane and the Adagio

The best DAC near that price is the Ayre QX-8. It is closer to 6 with the Network card, but it will sound far better than others less than $9k! I’ve heard many of the other touted DACs.

I would highly recommend the Aqua La Scala.
It is R2R, upgradable, with good set of connections and beautifully sound. Although the rest of my rig is way above its price point, it  does not feel at all as a weak point and it is performing fabulous.