Line level adjuster?

i put an set of auxillary RCA inputs on my 02 altimas factory stereo.  but when i hook it up to my MP3 player the volume doesn't match the volume of the radio or cd player.  i thought i had seen a little device that will do this, but i can't find it now. 

It needs to increase the volume...not a lot just a bit.  Please tell me i didn't just dream this up!

This was the same problem I had in my truck.  The mp3 player doesn't produce the amount of voltage needed to keep up with the cd player or radio.  My truck has an aftermarket Head-Unit and I just adjusted the SLA (Source Level Adjustment) to match the volume. 

For your situation, I think some sort of line booster would work, but I don't know much about them.  An aftermarket head-unit would be your best bet.   Mine was $150 (Pioneer DEH-4700) and it gets the job done.  It is probably even less now because it is last years model.

yeah i agree with j_darling about the aftermarket would be the best option. if you do a pioneer with the prefix

DEH-P(model number here) then you can get a PIO-RCA or CDRB10 auxiliary piece that goes into the blue changer port on the back of the pioneer radio and then use the SLA (Sound Level Adjustment) to tune your MP3 close to the CD's level. also, if you get a DEH-P(model number here)MP that means the unit will play mp3 cd's. hope this helps.