That's a tough one. Buying direct doesn't guarantee you'll get the proper transformers, or even a unit directly from the original maker that isn't a knock off.
There used to be a site in Chicago called Pacific Valve that had units modded for the American market with proper trannies and were well made. Their inventory started to shrink some time ago and now they are under new management.
Their site is pacificvalve.us and it is under revision since I last checked. Their inventory is now broader and if they operate under the same ethics as the last owners, all your equipment will come with a warranty and it will be spec'd to US standards.
A lot of the lines they carry are sold in Australia and get good reviews and I still have a Classic 6.1 integrated that I should sell, but it's well made and sounds rather nice so it just sits in a closet. I'll sell it someday, at a nice loss.
All the best,
Nonoise
