Lots of good advice here. I think that the 2 extra speakers in the back that turns your system from 5.1 to 7.1 should be viewed as "complementary." In your system, they are least important by a very very long stretch. So do not spend money getting two extra speakers if it means cutting somewhere else in your system.
Joncourage, I might be missing something here, do you plan to use the amps in the Onkyo?
Joncourage, I might be missing something here, do you plan to use the amps in the Onkyo?