Crap pure crap, the D1 quality and SMSL customer service, or should I say their completely non existent customer service. I bought this D1 from drop after all the hype. I got it MANY months later, which was ok with me. Then, I was in the hostpital from Nov 2019 till now. I plug it in and sounds good, and less than 2 hours into it, it is not recognizable by any OS through USB. It refuses to give descriptor for itself. It shows "locked" when the USB is plugged and "unlock" when unplugged. So, okay lets try Optical... NOPE same thing. I have tried all tricks suggested by people, like 15 different things. None worked and I know a lot of people have the same problem as me. Drop ends support after 30 days and SMSL says 1 year. So, 3 months ago I tried to get to support and RMA. Nope, email is never answered at all. Nope, can't get through to support/customer service by phone AT ALL, and its expensive because I have to call China. On top of that, I have to say awak the whole night to try again with the phone because of time difference. 3 months, nothing. Zero. $850 down to trash. I will NEVER BUY SMSL AGAIN, NO MATTER WHAT THE PRICE... CRAP PURE CRAP! Stay away, it looks nice but if yours become a nice brick to look at, what use you have?