Speaker Sound

Put jumpers in and be done with it. If you're thinking about bi-wiring for sound improvement, you're looking in the wrong place. Go with bi-Amping.

@fiesta75 +1

One could use a coat hanger as jumpers, just not a plastic one.

Or use speaker wire as jumpers.

Something sounds wrong.  PSB makes pretty good speakers and certainly don’t design speakers with the glaring flaws you’re describing.  I’m guessing there’s a problem somewhere and replacing jumpers won’t likely fix it.  Bi-wiring budget speakers seems silly.  If anything, demo some jumpers and go from there, but something else seems amiss. 

Do I need jumpers with Biwire speaker cable? Will the cables be enough?

The theory of bi-wiring is that separating the current of each driver improves clarity.  If you use jumpers and bi-wire you are eliminating the benefits because now the current flow will be equivalent in both sets of wires.