Dragonfly uses 24 bit ESS Sabre DAC, whereas my Yamaha RX V475 has 24 bit Burr Brown DAC..
To all audiotechies, does this really justify making investment of another 10k... Will the sound be really different from AVR?
Only your ear and budget can answer that for you.
In audio (as with all things high end) the ROI decreases as you go up the ladder...
I would caution against "fill in the gap" purchases or even purchases that give you the "bump" to make you feel better... even incrementally.
In other words have a game plan. Decide what kind of setup you want to end up with 1 year, 5 years and 10 years down the line. Once I made that decision (and it was a PC based setup for me) that also decided the direction of all my purchases.
I've spent on an Apple rig, Amarra player, etc. and even the DAC upgrade is based more on how it integrates and plays with a PC based setup (I'm probably getting Wyred 4 Sound), but its not based on how it sounds as a standalone device.
So in other words, have a gameplan and let that decide your upgrade path. Simply buying individual components will only give you short term buyers joy and long term buyers remorse and something I don't advocate.
PS - If the Yammy sounds good then stick with it. I've not heard your particular model, and truth be told I'm an Onkyo fanboy, but I've personally recommended and helped buy the award winning Yamaha RX-V673 & Yamaha RX-V675 for a couple of friends. I personally like these 2 models for their sound especially across all genres of movies and if they perform even decently good for music then its highly unlikely a 10K or even a 20K DAC will upstage them.
I've already mentioned that on this side of 50K the Asus Xonar series will hold its own against most DACs... at least the main branded ones I've heard.