4 pair speaker selector for Zone 2 adequate?

Hi everyone,

I am building a home theater in which I am using the Onkyo TX-NR609 as my main receiver. I will have a 5.1 system in the main theater room, and I have four other rooms (outdoor covered patio, nook, dining room, and loft) that I would like to power through the Zone 2 output of the Onkyo via a Niles speaker selector.

My questions are:

1) Will the Onkyo be able to handle this load with the Niles speaker selector or is it too much for the Onkyo?

2) Will the volumes of the 4 rooms connected to the Niles speaker selector be adequate for mostly background music? I realize I can wait and see according to my taste, but I figured many of you may have already tried such a system and can speak on experience.

3) If you are recommending I NOT go with this above system, what do you propose instead to power these four rooms? An additional amplifier between the Onkyo and the Niles? A couple of Sonos ZP-120's (one for two rooms each)? I mention Sonos because I am going to have one ZP-90 connected to the Onkyo but I don't need too many unique Sonos zones, so I'd like to keep it simple if possible (why I proposed the initial plan).

Any thoughtful comments appreciated, thanks!

Thanks -- just curious if you could be more specific. Is your reason that I won't get enough volume out of the system? Or is it too much of a load on the Onkyo receiver and your concern is that? Something else? Thanks.