I hooked up a amp and the sub and it was working fine. I lend my buddy a sub and used another one it no longer worked. I use another sub and try it and it no longer work with any subs. The amp has power. I'm 100% sure the subs are fine. The speaker wires look fine. So what could be the problem. Not the RCA wires too.

If anyone can help me out pls PM me or reply me back thanx. Appreciated.

What can i check? Change speaker wires and see what happens?

ohm meeter on the speaker wires to the sub (disconect from the amp) if it reads a number the sub/wire to the sub is fine.

you could check the connections inside the box, they could have gotten jarred in the changing of the subs. I'd also double check thoose RCA's.

I used the multimeter to test it. There are # and the installer told me my amp was no good. Something inside might have been gone. There are power going to the amp and the amp lights up. He said my preamps are probably toasted. How can i check that? Also how can i check the - and + terminals. Could the channel for the - and + be no good. Let me know. Someone pls help me. If it don't work i will buy a new amp.

Testing RCAs is easy-ish.

First, verify that ALL connections are good (+ / - and remote). Then, verify that the speaker IS in fact connected. Then, grab a portable CD player/tape player and connect one of those 1/8" phono jack to RCA adapters to the CD/Tape player and the amp. If the amp plays what's on the CD/tape player, RCA inputs work fine. Make sure the amp is ON when you try this.