I spend quite a bit of time in China and the main point here is that even if you see any half decent valve kit (some of it is creeping into the malls now as it's becoming more mainstream) it's likely to be the sort of stuff you can get here fairly easily. However, you will probably be asked to pay twice or three times what you can get it for via Cattylink/
eBay etc, and it will definitely be 220v so you won't even have the minimal warranty you get when buying mail order.
The local retail price most likely won't be displayed but will be given verbally (local retail in China is increasingly steep), but even if your mandarin is fairly reasonable you won't have the same ability to cut a deal as a local - most department stores regularly negotiate a big chunk off off the asking price in-store (the percentage depends on what the line is - you can even do this with shirts, jackets etc) but as a 'rich foreigner' they won't be bending over backwards to give you maximum discount.
Increasingly Chinese shopping is becoming polarised between the big city malls, which sell expensive imports alongside local would-be premium brands at hugely marked-up prices (for name-brand-purchasers to show off the logos and brag about, like many people used to do here before the whole austerity thing), and local shops/night markets that sell a combination of cheap junk and knock-offs. The above applies pretty much anywhere these days, but especially Shanghai, where conspicuous consumption is a way of life for a privileged sector of society and where foreigners are expected to join in the madness.
Hong Kong is a little different, as is Taiwan, there's a thriving enthusiast hifi scene in both places, a more laid back approach to dealing with foreigners, and back street shops (if you can find them) where you are more likely to see interesting stuff if you look in the right places. It won't be cheap in there either though.
Anyway, by all means have a look about, but bear the above in mind. Even when I go to Japan (which is 100v) I tend only to buy non-powered stuff like cartridges and related bits due to the voltage issue. China has some rather nice quality souvenir stuff, but in maybe 10-12 trips over the past 7 years I've never bought any hifi there.
