Joe,
I just did something similar with my system. You need a receiver with pre-out connections for the front speakers, these go to one of the inputs on the XS which has unity gain, not sure what input that is as I use an 82. The receiver then powers the other channels.
One thing I noticed while looking for receivers, is it tends to be only the mid to high end receivers that have pre-outs. I ended up with a Pioneer SC-LX75, one down from the top of the range, but last years model, so I got it for 1/2 the price of the current SC-LX76, and the only changes between the two are the new one has 8 HDMI inputs rather than 7 (I have only 3 devices connected) and 4k up-scaling but as 4k TV is several years from being remotely affordable this is not a problem as far as I am concerned. And it sound's great, especially on good DTS Master HD blu-rays.
As long as you don't need all the very newest bells and whistles, such as 4k up-scaling, then there are some relative bargains to be had by hunting out 1 generation behind receivers, as all the manufacturers seem to refresh at least once a year. I paid just over 1,000 euros for the Pioneer, the current model is around 2,000.
There are several good threads in the Home Theatre room on connecting everything up and configuring it.
Simon
