Polk 505 sub hook up

My Polk 505 sub just stopped working and I am trying to figure out if the way I had it hooked up was the reason. I have it set up for home theater through a denon avr3400 using the lfe input. I also am feeding it a signal through the high Level from a 2 channel luxman receiver for music only. I built a switch that allows me to choose what power source is feeding the front speakers. I accidentally had both the denon and luxman on at the same time so the sub was getting both lfe and high Level input. A week later the sub started acting up and now does not work at all. I would appreciate any input