I have Mirage OM-R2 rear surround speakers that are rated at 80Hz - 22KHz. I have them connected to an Onkyo TX-DS898 receiver and during set-up configured the rear surround speakers as 'small'. Onkyo says that when you set-up speakers as 'Small', all frequencies lower than 80Hz will be output to the subwoofer. Do I need to set my subwoofer crossover to 80Hz?? Are frequencies lower than 80Hz sent to the rear surround channels??