We've definitely made huge efforts to improve delivery times over the last couple of years. Not to say there won't be times when parts availability could be an issue, but we are doing everything we can to make sure you guys don't have to wait like some did in the past. I hope you guys enjoy the amp!
Regarding the Holo DAC, I did a bit of comparison (using a Surface Pro 3 as the USB source) with and without the Singxer SU-1, and found the sound a bit thin and lacking body when using the USB input as compared to the SU-1 into the I2S port. Not bad by any means, and it still had the characteristic natural smooth detail of the Spring, but lacked a bit of weight. Being that I was doing that test with an electrostatic rig, which is most showing of that sort of flaw, perhaps it wouldn't be as noticeable depending on the headphone rig used. However, an introspective system like a Utopia, HD800 variant, or Susvara on a GS-X mk2 would be quite likely to show that difference.