Although many manufacturers do have some or all of their units produced in China, the differences between buying direct, and a large American company purchasing from China are.
1) Quality Control - Not only do most manufacturers in the states do their own tests when product arrives to them. They buy hundreds of thousands of dollars worth of equipment, so the Chinese manufacturers make sure to pay a little extra attention during manufacturing and testing of the units purchased by the major American companies, they do not want to lose these big accounts. DJ's that order 2-10 lights direct do not get the same care from the big Chinese manufacturers, as they are only a tiny portion of sales, and normally are not return customers.
2) Quality varies between plants - There may be a dozen factories in China making a very similiar light to one another. The reputable American companies occassionally have reps visit the plants in China, to oversee things, and have a good idea of which Chinese manufacturing plants to purchase from, as they have seen first hand the manufacturing techniques, quality control, and R&D facilities of these manufacturing facilities.
3) Spec'd parts - When a Lighting Company makes a purchase of a specific light they contract to purchase a certain quantity. This gives them the power to dictate certain parts be used (ie gobo's in moving heads, power supplies, lens for optics, LCD display and controls, ect.) Say you order 6 moving heads from a Chinese plant, there is the possibility that they run out of a certain gobo, they will then just substitute a different gobo during manufacturing. So you may end up with 4 moving heads with one gobo as the third gobo, and the other 2 have a completely different gobo in that slot. As well as different power supplies, or control boards. I have seen a DJ once on djforums who ordered 4 moving heads and the front LCD panel only matched on 2 of the units. 1 had a blue display with buttons, 1 had a blue display with a knob, and 2 had red displays.
