I see questions about AC lights a fair bit here.
Are they common in the US ? Over here in OZ/NZ , everyone (on the auschristmaslights forum) is encouraged to convert them and run them as DC . Depending on the type , the conversion is either as simple as cutting off the A/C plug and controller or in some cases opening the converter and shorting one connection.
We then use either Ray's 3 or 27 channel controller or other boards and drive them off the DMX output of various controllers. It also means that you can take one AC set of lights and split into smaller sections.