I will add my 2 cents in as this board has produced better results than I anticipated and I feel that with a few tweaks it will become very popular.
Here is the priority I would suggest:
External power supply while attached to VIM of Edge-V. Ideally power VIM/Edge from Tone Board through GPIO so that a quality power supply could be used. Good clean power is critical for high end audio so a DIY (Salas) or off the shelf (iFi) would be a huge benefit.
I2s input to Tone Board. There are several “isolator” boards that improve the audio by having better clocks and/or signal/power cleaning features. Most of these are I2s and having a functional I2s would again open more markets.
Hardware volume control. Software volume control is less than idea (it works fine in most cases but I am looking at the high end applications). Yes it is better to have the volume control on the preamp but the ESS has the ability built in for hardware volume control so itis a good solution for those wanting to keep components to a minimum. There is a reason audio players such as Mood and Volumio give you the option to use hardware or software for volume control.
Balanced out for me is not a priority. Sure they look great and you have bragging rights but how many amps require balanced input?
I am no expert but I do fit the market segment that you are selling to and I am involved in a market that you are not reaching as much as I think you can.