Thanks for the suggestions gunslingers. After the problem was posted I tried one more thing. Instead of using the line level inputs from the Velodyne sub to the 950's sub output I used the speaker level terminals on the Velodyne. Basically I connected the main front speakers (Mirages M5si) to the Velodyne and from the Velodyne back to the 770 amps main speaker output. I bypassed the 950's sub output. FOR some reason connecting the Velodyne's line level inputs to the 950's sub output results in noticebly less bass output and its not as deep. I now hear more, deeper bass with the impact that I was used to and the overall sound has improved. I can also adjust the volume at the sub without increasing the frequency (occurance) of the popping sounds . However I still heard an occasional popping sound at the subwoofer when playing movies, some times with loud passages (explosions) and sometimes with not so loud passages. I have not heard the popping sound when playing music even at high volumes. The subwoofer sounds clear and powerful when playng my Cd's. I am going to substitute the sub with an identical one within the next couple of weeks to see if the popping persists. I'm still perplexed with this popping problem since it was not occuring with the lexicon.