Hello . I have a Onkyo TX-SR505 receiver , and my issue is that it cuts off when the volume reaches around 53 . I understand that it could have been an issue with my speakers , so I unplugged everything and it is continuing to shut off ,so now I am completely lost. I hope someone can help me understand my issue.
Only generalities without specific knowledge of your specific receiver.
If the problem was related to the speakers, then I can only assume you mean to say you were driving low impedance speakers or, at the least, speakers which dipped down too low at some frequency for your receiver's current (Amperage) capability.
Most mass market receivers simply are not built to maintain sufficient Amperage into the load of the speakers uninformed sales people push with these receivers. If the amp cannot produce the Amperage, and maintain that current delivery over time, the amplifier will shut down in order to save itself.
However, the constant and repeated stress and heat produced by the amplifier will weaken the various components supporting the output transistors. Excessive heat build up will cause components to drift from the OEM specs and tolerances.
Eventually, the amp will require service by a qualified technician. There is no way for a consumer to do this troubleshooting since it requires specific tools, equipment and information not typically found in the average user.
You can contact Onkyo and ask for any assistance they might provide. I would guess you will get the same answer I've provided here.