[nhhiep]

First of all, thanks for your advice. Here is my situation. I have a standard 10 speakers system. I will install an amp and sub in the trunk. The MTX amp has both speaker-level and RCA inputs. It also has "Smart engage" feature that turn on and off automatically when using speaker-level input, no turn-on lead is needed, very convenient this way.

My question is which method to do to get better sound?

1. Tap into subwoofer output and connect to a high/lo converter, Stinger SLOCII, to get RCA for my MTX amp.

2. Tap into the input wires at the factory amp coming from the head unit, and use it as a speaker-level input for my amp. I am guess this method would yield better quality since there is 1 less component in my setup (the high/lo convertor). Wiring diagram at this page. http://www.e90post.com/forums/showthread.php?t=52193

Another question is I noticed that there is an unused 4 pins connector (2 optical, 1 red, 1 brown) next to the factory amp. I am guessing that is for the CD changer option, which I don't have. I also noticed that after all doors are locked for about 15mins, the power is cut at this connector. Can I use it as a turn on lead, instead of running the wire all the way from the rear power outlet? I am surprised no one mentioned about this since it would be less hassle.

Thanks all

[nhhiep]

anyone?

[1sikbmw]

i suggest using a hi-lo. i have 3 JL subs and a JL amp. i just asked bmw for the schematics (i think thats how u spell it ), tapped the sub wires, connected them to the hi-lo and ran the rca's to the other end of it. Really easy, and so simple. great sound btw!

[nhhiep]

All the wiring diagrams are in my original post. I am just wondering which option yields better sound.

[1sikbmw]

i tapped into the rear speakers and the woofers, needless to say, the woofers gave way better sound!

[tintivilus]

First off, I don't think there's a whit of difference between using an outboard hi/lo convertor with your amp's line inputs vs using the amp's speaker-level inputs (its built-in hi/lo convertor). That being said, there are a few things to consider...

- since this is a sub, make sure the signals you're tapping have the low frequencies you want. Tapping the factory sub or woofer lines are going to yield better results than tapping mid/hi or full-range signals.

- garbage in = garbage out. if you turn up your factory stereo until its distorted, you're also feeding distortion to your sub amp.

The big problem with hi/lo conversion is that you're stuck with whatever distortion your factory amp is adding to the signal. Try to keep this to a minimum and you'll be happy.