car audio help

hey, i recently put a 10" jensen sub and an MTX amp in my car and I have the exact same wiring set up as I did with my old amp and the system worked great. All of a sudden, i stopped gettin the sweet bass with my old amp so i bought a new MTX amp. ever since ive had that amp, i still havent been able to make the system work. How could the system have worked with that wiring for several months and then it just stopped working and now i cant get it working again. Please give me some things to look for and help me get this thing up and running again. thanks.

josh