No i have a different DAC sorry. I just wanted to point some in the direction as I found AOIP kills USB.
I am unsure on your main system chain. Your NAS is external disk drives? You need a PC or Mac or network player to use those files unlike say a Perfect Wave DAC which handles external disk storage? The Dave doesn't do that?
My system is Mac Mini - Ethernet 1000T out - RedNet 3 - SPDIF out - Audio Note DAC 5 Special.
The effect of getting rid of USB is dramatic. It isn't just Ethernet DHCP, it is Audinate protocol designed just for high end audio transfers (from the pro studio sector).
I haven't tried optical. I have read varying reports on it from ok to bad, not so many that are parsing it's performance.
Basically with USB the treble was never accurate or musical to me, too edgy and sharp, digital. With AOIP it is fluid, smooth as silk and still as transparent. Bass is also faster, deeper and more textured, less 'one note' on dance material for example. Female vocals are magical, soundstage is wider and more 3D. It just seems to remove any noise or haze and peals back to the master tape.