I just got this sub last week and I have a small issue. First I have it set up thru the line level input to my Dennon AVR 5700. It does sound very good and blended great with my Concerto's however...... It makes a loud thump when I turn the cd player on/off and when it changes tracks also during dvd playback each time the previews change or when changing something at the menue screen. I tried the high level (speaker cable to sub then out to speakers) and did not have that problem but it did not sound as good. So..... Is it the sub or my reciever??? Any Ideas.