If I connect the Vin and GND of the DAC directly to terminals of one of my motors without the amplifier, the motor can move in both cw and ccw directions, but it's turning very weakly/ slowly. But if I insert the power amplifier, the motor turns faster & 'stronger' but it only turns in one direction. Is there something wrong with my connection? I only connect the Vin from DAC to to pin 1 of LM675, motor terminals to pin 4 of LM675 and the power supply's ground, and I do not connect the DAC's ground to anywhere.