ich habe das dazu gefunden:
Line Level Converter
These handy little devices, line level converter are a must for those of you out there that have new vehicles with great systems, like the new Nissan Altima with the Bose system package (Joey). In short what this little device does, is reduce power coming from your head unit (tuner). This allows you to connect into one of your existing wires (usually the rear deck) then connect rca cables to your amp powering either your subs rear speakers or both. This cannot be accomplished many times due to the amount of over current going to your amp causing it to just cut out. By reducing the wattage going from your head unit to the amp, you can allow a low level signal to either be patched into a equalizer that feeds to a amp or directly to your amp. By using this device it should solve all or most of your cut out problems. Most of these devices are adjustable so you can adjust them according to the sound level that you play your music at. The wattage sent from you head unit goes up as you turn the volume up so you may have to tweek with the settings to get your optimal performance settings for your amp.
soweit ich das verstanden habe, ist das ein adapterstueck, an welches man die lautsprecherausgaenge des radios setzt. diese werden dann in ein signal fuer chinch umgewandelt. das oben beschriebene geraet ist scheinbar regelbar etc. tut aber nun nichts zur sache. ich hoffe es hat geholfen ;)