I built a Sonosub several months back and it sounds great with my Samson 700 amp except for the fact that I couldn't adjust the volume on it. Unfortunately, my main receiver doesn't have the ability to adjust the subwoofer volume independently. Anyway... So I ran the sub out from my main reciever to an old receiver and am using the receiver to power the sub. I can adjust the volume and therefore can get it much louder but now I get a farting sound (the best description I can give) in most movies. A specific seen would be in the second rocket launcher/car explosion scene in Ronin with Robert De Niro. Is this my sonosub (a ported tempest sonotube) or is it my old 60?? watt amplifier I am using to power it? How can I check? Seriously, thanks for ANY help you can provide!!!