Yes, reputation.
1. But also simply geographics. No offense to Vietnam, but they dont have the number of folks with big money to spend on toys, compared to the US. So there is a smaller number of higher end products available.
E.g. We often forget how spoiled we are in the US with all our choices, but it is not the same around the world.
2. Reputation in the sense of which products get hype and which ones dont, just like in the US. What is hot right now? I see more and more forums on Asian brands- Denafrips DAC, Jay's Transport, Kinki something something. And people in the US are jumping on that bandwagon. Same thing in Vietnam.
3. IME, the audiophile Asians I have met tend to like a smoother sound, like the ESS Sabre DACs with 1000x oversampling. It is still detailed, but smoothness and lack of grain tend to be the preference. Not to stereotype or anything, just my experience. Which is interesting b/c the older WAdia/high end DACs that are quoted above are Burr-Browns, which to my ears have always been more fast, nimble, high res, high dynamics but a mostly analogue sound (the better the support circuitry and power modules. )