Aftermarket sound with factory headunit - calling all sound pros!

So I'm attempting to put a system into my 09' M3 GT with some components I've salvaged.. Just having some trouble choosing what amp to buy with the ridiculous amount of choice there is out there..

Anyways, here's what I have so far:
4x Alpine Type-R components (older model, like 2004-2006, and both pairs different sizes)
1x Alpine Type-E sub (likely an older model too)

And I figured getting a 5-chan amp would be the way to go.. Not quite sure what the difference between amps is but I figured a better quality one (JL, Alpine, Polk) would be the way to go..

The idea is to keep the stock HU (don't want to lose trip/fuel comp and steering controls!), which would mean using some kind of line-out converter for the M3 stereo to interact with the amp.

So let me get down to the point.


What I'm trying to figure out is:

1. What is the best factory integration system/line-out converter out there (JL cleansweep, Audiocontrol LC6, etc.)?

2. Are there any decent 5-channel amps that will match the quality of the speakers at a reasonable price? (looked at JL slash 500/5, Alpine, Polk and JBL so far)

3. Any tips on choosing an amp? I've heard that various brands have different wattage ratings (ie. a JL 500w amp's wattage is similar to an MTX 1000w amp)?

Thanks for your help!

Cheers,
hzavery

1. You will need a Sound Processor, not just a LOC. I have the same year and model/trim as you and our headunits will cut out highs and lows (has nothing to do with Bose) and they will affect you achieving quality aftermarket sound. The best way to go is LC6i as its the best bang for buck. If your going JL, your paying for the name but honestly is a great unit from what I read. Just you can achieve the same results with the LC6i. Theres also the MTX reQ5 but I would recommend the LC6i as I hear better things when compared to the MTX reQ5

Phillie is right LC6i is the best route to go if you want to keep your stock head unit I tried the REQ5 and had a horrible time but another guy on here Dave The BMXER had no problems (and it's not a coincidence that we are both named dave, both tried the same product, and both have white cars....lol / Dave if you read this we should meet up at some point lol)

If you want the absolute best best best sound go with two amps one mono (or two channel if you prefer depending on what sub you buy) and one 4 channel amp for you speakers

Amp wise Pioneer has great Class-D digital amps that are very powerful and very small, and JL's amps are all around good sound quality pieces.

Finally by pulling out the stock head unit you won't loose trip/fuel econ just steering wheel controls, however that adapter is only $50-$60 and if you end up replacing the stock head unit its a small cost.

I didn't have no problems, I just was able to get my problems to a manageable level ;)

I have another thing to try eventually.

I'm just curious to know when clipping occurs on our stock HU. Does anyone have the LC6i and see when the "maximum" signal lights up when you turn your volume up? I read somewhere thats the point of clipping and it indicates it.

Hey there, I actually have a Brand New MTX RE-Q5 for sale. Never been used or installed. Awesome piece. Let me know if you are interested!!

Been spending all day looking at various audio processors and just saw that Alpine is bringing out a new sound processor-- the PXE-H660 (http://www.alpine-usa.com/product/view/pxe-h660/)..
Looking like the LC6i is the better option (found the H660 on ebay for about 400, still way expensive for my budget).. And as far as the amp goes, just about to pick up the PDX-F4 off ebay, looks like a decent amp with a small footprint.

Also, fyi, I don't have the Bose system as I got the budget GT..lol