I posted this same message on one of the other threads, so I am just putting it here for Kwangsun's benefit. I do not have the 812V2, but I have 2 of the 960 versions (modified and dual core), along with the 770 and 770c.
I think you might want to consider this issue a little bit differently. The 812V2 was one of the first DAPs in the current line of Xuelin players. It has been out for over 2 years. There are some nice reviews of the 812V2 in Head Fi, and overall the reviews were positive. But you have to keep in mind that the 812V2 was released even before the first version of the 960. Over the past 1-2 yrs, the 960 has been modified twice, whereas the 812V2 has not been changed at all. Additionally, the 812V2 was essentially the precursor for the 960. I'm not trying to suggest that the 812V2 is not a good DAP, I just think that attempts to improve the Xuelin players in any way have not involved the 812V2. The 812V2 is as large as the 960, but it does not have some of the features that the 960 has (dual core, coax out, thinner analog dial, firmware upgrade, etc). The 770 models were Xuelin's more recent attempt to maintain high-quality sound in a smaller, more stylish package. I feel that the 770 is currently more popular than the 812V2, so most likely Xuelin will continue to support the 770 for some time to come. With the emerging 800 model due to be released sometime later this yr, the 812V2 may eventually be discontinued. The 800 model represents a major shift for Xuelin in terms of style and components, so the future for the 812V2 appears limited to me. As you know, Xuelin has already discontinued the 760. So, to finally get to my point: If I were to start over with the Xuelin players (knowing what I do now), I would either wait on the 800 model to come out or if I felt I needed a very nice DAP for a nice price before the 800 is released, then I would buy the 770C.
In regards to vendors for the Xuelin products... I would strongly recommend that you buy from a very reputable vendor. For a very personal reference, I would only trust Penon Audio or bigbargainonline on eBay (same seller). If you have a problem with the player that you receive, you can bet your life that Penon Audio will do what it takes to make things right... I bought my initial 960 from another vendor on eBay (before I was aware of Penon Audio) because I could get it for less money; turned out to be a major mistake. I have personally not had good luck trying to work directly with Xuelin, but Penon Audio has provided a great "bridge" between me and the company when I have needed help. Good luck.