If the unit is still under warranty definitely give Sony a call. This is an ES series receiver, so is more robust. They even provide specs for four ohm loads, which is rare in midfi receivers, especially AV receivers.

I have a Sony STR-D5300ES. My original unit had a firmware issue. I called Sony and within two days I had a new receiver at my door. They also provided a pre-paid shipping label to return the defective unit. This was after having the unit for several months. I can't complain about their service.