DJM 2000 Power Voltage confusion. 110V or 110V/220V universal??

Please answer me with accurate information.  I bought my DJM 2000 from the U.S. and you already know the caution printed on side of the mixer stated 110V. I took my djm to China with me where the standard is 220V.  right before I thought about asking this question, I saw 2 of my friends pluggin in their newly purchased djm2000 from amazon directly into a normal power jack (220V) and the unit turned on with no problem, and have not heard any problem about their mixer til now. Remember, they purchased the DJM from amazon.com so theirs is also U.S. version with 110V printed on the side.  I'm just hesitating about trying my djm directly to 220V power, because til now I havn't found any information about the actual power requirement being universal.  I couldn't take a 2nd look at their mixer yet because they locked it up and went on vacation.  

Specialist, please contact the production department and be responsible to tell me if I could bypass using a voltage convertor or not, it's really a pain to use a convertor.  if it is actually built as universal and just printed differently, then I would love to get rid of the convertor