Just came back from singing karaoke with my friends, my brothers and their girlfriends. We were at the Orchard Cathay Cineleisure's K-Box and I have to tell anyone that is thinking of going there: DON'T! The environment is lousy, room is too small, air-con is too cold, equipment is faulty, and everything is a tad too expensive for their worth. As for their service, I will have to say the staff is more of being clueless rather than bad.
Another K-Box outlet which you should avoid is the one in Jurong due to the poor condition of their toilets.