Is the pioneer a different impedence rating then the one you had in there? Id be willing to be that is the problem. Is a red light coming on? If so the amp is probalby shutting down to protect itself. 150 watts isnt much but it still shouldnt be shutting down. The sub being to powerful sounds like bs if thats what he actually said. Yeah you may need more powerful amp to get the max performance out of your sub but as long as its loud enough for you and your not getting distortion then it should be fine.