I just bought one of these yesterday for a friends home theater. But its still on the way, so I don't have it yet.
Go with Hz on the EQ (just a guess), and read the menus on screen, you'll find the manual setup. Make your Sats small, if thats an option. If you have a sub, set ALL to small, hook sub up to LFE (low freq. effects).
Until you can replace those Sonys, don't drive them hard, or you can kiss them goodbye real soon, i.e. a blown woofer or two.
Kinda in a hurry, but I'll try and find the .pdf at Onkyo for the 605.