It's time to give you a feedback about my DX3 Pro failure.
I had a problem with right channel (headphone output) reported and described some time ago, as you can see below:
And the video...
Finally I've got a 1902 version some time ago with some changes like different power supply, new remote (RC-15A), plastic caps on RCA connectors, front LCD protector made from glass and AD8620 instead OPA2140.
It is interesting because my version is 1902 with new remote and power supply. I thought that starting from some point all further versions of DX3 Pro will look like that.
And It seems that AD8620 is not put into all production devices. I've got the following response from Topping:
So, front screen covered by glass seems to be more solid (previously I could bend it under finger's pressure). Remote seems to be better as well (see photos). I have also aluminum remote dedicated to DX7s and self-learning remote bought on aliexpress for everyday usage (blue buttons). I use DX3 Pro as a preamp so I wouldn't like someone from my family (even me) to accidentally switch it to DAC mode and blow my apartment
Regarding AD8620 - I don't have any good headphones and I can't confirm quality differences. I put some cheap in-ear headphones and dac was playing for tens of hours to make load test. Everything is working well so far.
I also don't have a long 2mm hex wrench to confirm if AD8620 was install in manufacturing process or manually but at least I can confirm that indeed it sits inside
(I could pull board a little and take a photo).
To summarize I would like to say that Topping Service is really good. I bought my unit on aliexpress but decided to replace it directly via Topping. They sent new unit via DHL so I got it after about 5 days. The only disadvantage is that I had to clarify for customs it was a warranty replacement, not new purchase. Finally they released it from duties. They're providing really good service.