I'd be surprised if the Sony ES receivers were unable to power the M80s. The 4ES and 7ES both say "Impedance 4-16 ohms" and have a 4/8 ohm switch on the back.

Here's a link to the rear panel, if anyone cares to see it.
http://www.crutchfield.com/cgi-bin/S-AsKb61SeB53/ProdView.asp?s=0&cc=01&g=10420&id=morephotos&pi=2&i=158STRDA7E&display=XL#morephotos