Finally, I decided the ONIX Alpha XI1 is my default dongle/USB DAC/DAP after choosing my preferred settings. There is a treble smoothness to impart a slightly analog presentation, but it is not meant to color the sound of your gear any further. I can understand why Andy said the XI1 is neutral with details, yet analog and neither clinical nor harsh, with good dynamic capability and contrast. So far I am satisfied with XI1's presentation. I will be getting a second XI1, and then I might also a/b test between the new/old units to see if burn-in effect existed or not.
For now, I based it on 55-70dB listening volume, stock OTG cable, leather case on Nonoversampling filter, Low Gain, firmware 01.00.03, Windows 10, used with easy-to-drive IEMs (none are dark IEMs). (4.4mm balanced output can be an option depending on synergy, but note higher noise floor in NOS filter.)
The stock OTG cable is because that's the only cable I was using, not because I chose it among other cables. The reason I started with the stock OTG cable is because from my brief initial impressions, the stock's synergy sounded more normal and I was trying to avoid coloration. Note despite the stock OTG cable likely not being single crystal or high-purity, the XI1 still sounds impressive with it.
