Charles, The basic precision of your standards is not really sufficient, as they should have at leat 10ppm / 50ppm accuracy. The more severe problem is, that you are lacking any transfer standards, i.e. transfer from your 2,5V and 596 Ohm standard values to the necessary Cardinal Points, 0,1V, 1V, 10V, 100V, 1kV, and Ohm ranges analogically. Therefore, you have no chance to calibrate your DMM properly without further instruments. Regards - Frank