Re: Kenwood KRF-X9992D
The Mission 704 speakers are decent depending on the conditions. I personally found them to be a bit bassy with harsh highs.
The Yamaha center channel is an older version of what they currently have. Although not much has changed. It contains 2 5.5" woofers and 1 1" tweeter. You might find it hard to match the Missions with the Yamaha. The 100W/channel of the Kenwood receiver might not be enough to push the Yamaha. You probably need to tap the Yamaha out at more of its max of 160W to get clarity from it. This would require a separate power amplifier as most receivers don't provide that kindof power per channel.
The Kenwood Receiver is the US model of the previously mentioned KRF-X9992D, with the exception of the power connections and consumption. Refer to the kenwoodusa.com support website for the owner's manual with detailed specifications.
The JBL PB12 is worth the $300 for the whole set as it has some decent crossover settings and retails for $480 itself. You will probably find the response time between the Mission 704s and PB12 to be out of phase. The Mission's reponse are much slower and this may cause a boxy, hollow, phased bass sound.
All in all I think it is a good deal for $300. I would use the JBL sub and rears and then get a set of JBL LCR to round out the system. The Venue series is pretty good and should go well with the PB12.
I would pass on the receiver and get an Onkyo 605 for $399 or something there equivalent which will give you more power, expanded features, and HDMI switching and upconversion.
Just my two cents.