Thanks uncle Dave & Gary.the output sounded as good whether from kb or mixer as long as I use a headphone but sounded completely different after the amp and speakers.My room is only 4mX5m so I thought a 100watts per channel amp and a pair of impulse 652s should be more than enough as I never turn the volume up more than half.My speakers are ceiling mounted.I don't have an equalizer.I tried playing with those knobs on the mixer and BBE maximizer but didn't help.(it sounded even worst without BBE)Some people suspected that my configuration might be mono but I am pretty sure it's stereo.What else can I do? Has it got anything to do with my amp?or speakers?or cables?