I had a similar problem some time ago. When I thought about it and the Engineer in me came out, I reached the following conclusion:
As the left arm remains in line with the shaft at impact the low point of the swing will be in line with your left armpit. This is slightly complicated due to the fact that as your spine (or sternum), leans back and forwards with varying
clubs, a line projected from your left armpit and down the shaft to the ground will point forwards with the driver and longer
clubs and further back with shorter
clubs. Clear so far?
If the ball is placed centre of stance (For example) and the sole of the club is grounded behind the ball at address then at impact the leading edge will strike the ground just behind the ball and have to either complete its arc by digging into or bouncing over the ground until reaching the low point (left armpit to turf line), otherwise you will be forced to lift up during the downswing to compensate, thus chancing a topped shot. Still with me ?
So, my answer is to address the ball with the sole of the club hovering just above the grass. This allows me to hit down crisply into the back of the ball, pinching it into the turf and taking a nice shallow divot just in front of the ball. The low point of the swing being just forward of the ball.
Try it at the range on a mat, you will get that nice sound of the club just brushing forward of the ball, instead of that deadly thump.