The -2dB point on the Kappa 9.1 II is listed as 27Hz. Since they are also acting as your subs, I'd assume you have them set to "large," which means we're not concerned about the crossover point. The -2dB on the Video II is 90Hz. Normally, folks look at the -3dB point when determining crossovers, so you could probably start out trying 80Hz as the crossover for those channels. I wouldn't go lower than 80Hz, and you might even try 100Hz just to see how it compares.