I have read about people who have stacked speakers (4 of the same speaker, one on top of the other), two sets of two. Just wanted to make it somewhat clear. What is the purpose of stacking and could I stack Pioneer HPM 40's/60's? If I did this, I would be running them through a Sansui AU-719 Integrated. What advantage do I gain by stacking?

As always, thanks in advance.

Randy