Did you contact their service center? You can get information (service center in hyderabad) from ..:: Welcome to Babbler Group ::.. as they seems to be the dealer of Q-Acoustics in India.
Just came across your thread at random.. It is highly unlikely that you can damage active speakers by playing loud. They have inbuilt protection and the amplification is limited in its power before it damages the drivers. That is the benefit of active speakers as compared to passive.
There could be EM interference from either a power cord or near by wireless router causing the distortion. But anyways what is the status with your speakers now.