Again, I would "borrow" a sub from your local retailer to see if that is the issue you are having with your system. If you can return the HSU, used unit then that would work out well for you. If you cannot return it then you may purchase an item that, after set up, you realize is not the issue you are having. If after you "borrow" the sub and see that it is the issue then return it and get the HSU, or use the HSU as your test item.