I think that if you have the stock head unit in a mercedes, it would make more sense to buy one of the new ones that play mp3s off a cd-r. It would be a little less convenient, as you would have to change cds every 250 songs!! or so, but I think the improvement in sound quality over the stock becker unit would be worth it. Plus, you would get the added benefit of line level outs so you could further upgrade the system in the future ;-)