So I upgraded the inlaws AVR to a 2807. We've decided to keep their older MK speakers but now I notice (DOH) that they are 4 ohms and the 2807 is rated down to 6 ohms. I read the "warning" in the manual indicating possible shutdown after long periods.

Now assuming that my inlaws don't listen to it loudly or for periods longer than say 4 hours, should this be an issue? Bear in mind that I can provide as much ventilation as possible, even including a fan right on top of the receiver.