Going to 160 volts is way over the top. Steppers motors start and stop each step, and there are (usually) 200 steps per revolution. To get better performance out of them it is normal to use about 5 times the rated voltage - which "encourages" them to accelerate faster, without burning them out.
I misread your first post, and you do not say what voltage the 0.83 amps is applicable to - there must be one.
Try testing across one of your coils and see what resistance the coil is. This will give you some idea. E = IR and all that. I would use about 5 times the rated voltage - any more and you then stand the risk of burning out the motor - not when it is moving - but when it is stood, because unless you build into the circuit some sort of current limiter, since steppers still have current going through their coils when stood, this is when melt down will occur. At 160 volts I would have thought that to be fairly soon.