Passive would allow you to use your existing equipment. Most passive speaker bars only do the front three speakers and you will still need speakers for the surrounds. There are a couple of multichannel speaker bars. Here are the ones that come to mind.
Atlantic Technology FS7.1
Definitive Technology SSA series
BIC Formula FH-56
Klipsch G-42
Atlantic Technology FS7.1
Definitive Technology SSA series
BIC Formula FH-56
Klipsch G-42