Pioneer Receiver sounding low all of a sudden

So I have this Pioneer VSX-518 that I been using for many years, And this afternoon, When I turn it on, The audio sounds very low and distorted, It was working fine yesterday however. I tried turning it off and on, unplugging it, unpluging the speakers, And the receiver still producing low audio. I had to turn if halfway just to be able to hear audio.

Any idea whats causing this?

Someone from the Home Theater Forum says it might be either the power suply or Cap that popped. Either way the Receiver still functions like normal, I just have to higher the volume more just to hear good enough volume from the receiver.