thats all you need if you buy from an authorized dealer. Most manufacturers know who they sold a particular piece to by checking the serial number on it. If they sold it to say woofersetc.com, they know not to honor any warranty on it.

I didnt say it in my other post so I'll say it now. Alot of what you buy online is either b-stocks or repaired items. The best chance you have a getting a truely new item is getting the previous years model. Those are usually sold off to unauthorized dealers after the new model becomes available.