I have a full size 71 buick electra with a "stock am/fm radio." I did at one time add a newer model cd player radio and 400watt amp for the 4 speakers I added 2 3inch rockford fosgate 15/30 watts speakers in front and 2 6x9 60-120 watt jensen's in the rear. That combination's volume adjusted nominaly. Now I setup the stock radio to the 400 watt amp turned the amp's gain all the way down and radio volume all the way down. Why is it full blast at the lowest volume setting? Also I made the radio's front left and right inputs branch to control both from and rear speakers because I have it hooked thru an amp.
The stock radio systems usually have 10ohm or so speakers connected, which will require more "beef" from the radio to drive them. The level out from the radio will be higher. Newer radios are probably meant for 4ohm speakers. I'll bet this is whats causing the high level.. You could probably make a simple circuit in-between the stock radio and the amp to fix this but I wouldn't know how right now, since it's been a few years since I did electronics
best bet. radio shack sells a lil speaker level to line level converter. works pretty well. its about 20 bucks.. I have seen them with a built in EQ for 30 but I can't rember where (it was after I bought mine) another place to check for that part would be www.partsexpress.com nate
