I'm answering my own question. Sorry to bother you all. I'm not a professional for electronics or electrical items but have limited experience in repairing such items. After opening primary speaker box and investigating wiring on its electronic board, I found that the wire connector having 5 pins (USB +, USB -, Aux +, Aux -, Aux G) had loose/pulled out Aux Ground pin. Moreover, there was an Aux out connector on the board that disturbed sound when touched. I suspected its metal base was touching other lanes on board and I fixed it by raising a bit. And thankfully, problem resolved! Perhaps one of these or both were the reasons that Aux was missing sound and giving noises specially on separate adapter. However Bluetooth was giving clear sound.