2000 Sentra Sound System?!?!

[wookiesZ28]

My friend has a 2000 Sentra. His problem is that his sound system sounds like total ***! I tried to look at it for him and found he has had xplod speakers put into the back, and the wires were just twisted together without any tape on them. But once I corrected this his system still sounds distorted. He doesn't have the factory deck, I'm not exactly sure what it is. But is there any idea why this sounds so bad? Would it be the deck? Or maybe the factory wires aren't enough to for the new deck and speakers?

Also on the left side it looks like there is a "mini sub" next to the xplod, that is factory installed. You can tell it does not work. And right next to it i found wires with a white plug, both male and female ends. On the Female end there is a tiny piece of circuit board broken off still screwed to the connector. I looked and looked but cannot find anywhere where this came from or goes to. I need help desperately on this one fellas!!

Maybe if you have wiring diagrams for this sound system it might help to solve some mysteries?!

THANKS

[sr20de4evr]

it sounds like ass, because Sony sucks

In the stock system the headunit powers the 4 speakers. The "sub" (if you want to call it that, I like to call it a worthless waste of metal) gets its signal from the rear speakers, and it has it's own little mini amp that hangs in the basket below it. The white plug plugs into it, and it carries the signal, power, ground, and remote lead for the amp. My guess is whoever unplugged it just broke it off and took part of the amp with it, that would explain the circuit board piece you found. Not really a waste, that sub actually takes away from the sound since it's so bad.

As for improving it, ditch the Sony shit and get some quality speakers, in the rear AND the front, the front speakers after all are by far the most important. If the headunit it has now is really that bad then a new one could be in order. You can find a low level alpine or pioneer pretty cheap on ebay if his budget isn't sky high. Come to the audio section here if you want more info, you should get more help there.
http://www.automotiveforums.com/vbulletin/f675