I'm glad you are realistic with "it is a sound bar after all". That being said I think you will notice a big upgrade with the Vision sound bar, especially in detailed midrange and highs. The vision even among newer models is near the top of the heap for sound quality with sound bars. I'm not sure how the bass in the vision will compare with two 6.5 woofers in the Zvox. I would guess the Zvox would have more output in the bass range, I'm not sure about better bass though. A small sub would certainly be a welcome addition to either system but in cabinet placement would not be recommended. A small sub to the side of that cabinet should not be too intrusive.