Do you have Base or HiFi audio in the car from factory? Do you have (3) sets of speakers (including the underseat subs)? Because if you do, you should be using a (6) Channel Amp
Obviously, you don't have the Logic7 system cause that amp would never work with that.
Personally, I purchased the JL Audio XD600/6 to replace my factory HiFi amp based on recommendation from 'Technic'
The JL amp is configured to accept the funky BMW HU output, has 6 channels for:
- CH1/CH2 -> Front Door Components (Mid + Tweeter)
- CH3/Ch4 -> Sail Panel Components (Mid + Tweeter)
- CH5/CH6 -> Underseat (Subs)
Note: this is setup for HiFi speaker configuration in my E92. If you have E90 or base system yours may be different.
Amp can power 4ohm loads @ 75W or 2ohm loads (Factory speaker rating) @100W for each channel. All channels have Hi or Low Pass Filtering with different Hz cutoffs, and Adjustable Gain Control.
Technic even sells a premade wiring harness including 4AWG Power/Gnd hookups that plugs right into your factory amp connector and then in to your new amp without cuttting any factory wires.
He also sells premade speaker connector pigtails so that you can solder them on to your new aftermarket speakers then simply plug right into factory speaker connectors without cutting.
That way, everything you do is reversible with no damage to factory wiring or resulting 'spaghetti warehouse'
>> When in doubt, your best bet is to contact the forum audio guru's 'Technic' or 'VP Electricity' one, or both of them should be able to get you straight away...