I had an Alpine CDA-9815. It's a 3-ch headunit (front/rear/sub) and it had some fairly advanced processing inside - i could set crossover points for each channel as well as time-delay (for distance so ...
I'm getting ready to buy a new car stereo (one of the new PlaysForSure stereos from Alpine -- CDA-9857 with the KDA-620M USB adapter) and the guy suggested running a power lead for my MP3 player so it ...