I had a Sony STRDB1070, rated at 100 watts x 6 channels. I always found it sort of underpowered. There is a website called ratesvac where some fella measured the actual output of various receivers. He figured the 1070 actually put out only 30 odd watts per channel. Can't comment on his methodology, but my experience with the Sony was consistent with his results.
You may want to check Sony's specs to see whether they claim the 80 wpc with all channels driven. In any case, If you like the Sony, I'd use it as a preamp and get some 2 channel amps for some power. I used 3 Onkyo M282 120 watts x 2 amps which I got manufacturer refurbished from ubid.com for under $100 each.