ya i dont know what they did to mine but i have my tacomas stock deck with a Jensen power amp and 2 Rockford 12's they charged me for some kind of piece the attached to the back of my stock deck which is prolly what the other guy was talking about
You can hook up your amp to your stock radio all you need is a 2 channel or 4 channel line converter, it depends on if your using a 2-channel or 4-channel amp. You can get them from Wal-mart but I would recommend going to Best Buy or a local stereo shop they should have them.
Yes. The 2-channel converter hooks up through speaker wire to your speaker wire on the back of the radio and gives you the RCA outputs you need. You can go to metraoline.com to take a look at them. If your trying to hook it up yourself you have to find a wiring diagram for your car to see what your speaker wire colors are and to find you amp turn on/accessory wire too. Usually its easier to take it somewhere to get it done. Should cost anywhere from $50 - $100 to do everything for you.
i did this before because it was cheaper but ended up just buying a new deck. the new deck made everything sound a lot better and was more convenient ie. subwoofer adjustment, hpf, filters for treble & bass, iPOD & aux. if your radio is not a double din and just 2 single dins you don't need a dashkit($20) you just need a wireharness ($7-10)
i did the labor myself so i just wasted the money on parts, but my advice to you is to know what you want before you start buying stuff and paying for labor if you're not going to do it yourself because you might just end up switching to a deck like i did. good luck