We're supposed to be metric here in Canada but I still think in feet so... 13 x 26 x 10 feet. Seems to me that 4 on-wall speakers (M3s or M22s, I would probably lean to M3s) should be fine for mostly-jazz listening (I'm interpreting that as *not* wall-of-sound rock).
Guessing you'll be running the 4 speakers as A and B pairs with A+B selected ? I'm not sure whether to be concerned about your receiver driving 2 paralleled pairs of speakers -- the reviews I saw for the R-S700 suggested it had two separate power amps (presumably to support zone-2) and so A and B were driven separately. If that's true then no problem for sure.
Hah... I came back to add "... and welcome to the forum" but JohnK beat me to it :)j
EDIT -- looks like you need a separate amplifier for zone-2, so the article that talked about the receiver having two distinct amplifiers for A and B outputs seems to be wrong. Here is the article, maybe I misread something:http://www.hometheaterhifi.com/receivers...ge-3-setup.html
Doesn't mean you will have problems driving two sets of speakers in parallel, just that it has to be considered. Looking at M3s and M22s the impedence curves seem well behaved so I wouldn't expect any problems.