From what I have read, lower bar height will start incorporating more quadriceps and will drop you into a half to full squat position. The end-result is that you will get more of a quadriceps workout, but you will sacrifice lifting potential for this since the body is more powerful in a half squat position. From a personal standpoint, I hate bending over more to grab the bar as I find I am more likely to attempt to squat the bar up than lift with my back. Grab some plates or steps and use them as stand-offs on either side of the bar to get the correct height.