Hey man,
I know the converter you are talking about and it isnt going to be as good as a line output converter that the car shop was talking about. I would recomend the Audiolink II from crutchfield. This product will use the rear speaker signals and convert them and give you an RCA output which can then be run to your amp. Another way is to buy a high quality amp with a built in "line output converter" and essentially this would do the same thing that the stand alone converter would do. I stress "high quality" because just any old amp with line out converter wont give you a good sound.
Good luck
peace
I know the converter you are talking about and it isnt going to be as good as a line output converter that the car shop was talking about. I would recomend the Audiolink II from crutchfield. This product will use the rear speaker signals and convert them and give you an RCA output which can then be run to your amp. Another way is to buy a high quality amp with a built in "line output converter" and essentially this would do the same thing that the stand alone converter would do. I stress "high quality" because just any old amp with line out converter wont give you a good sound.
Good luck
peace