LOC
 

Looking over the BSW Subwoofer install guide I'm wondering why a Line Output Converter is necessary. Alot of amplifiers already have speaker level inputs that converts the signal. What are the benefits? The con to me would be introducing additional noise to the signal.

If you're amp has speaker level inputs, a LOC is pretty pointless since your amp does the same thing internally.

It depends on the amplifier and the vehicle. Many vehicles you can simply connect directly to speaker level inputs if the amp is equipped. The issue comes in that many amps take speaker level but do not accept a balanced speaker level input. This is where the issue comes in. All vehicles that need the LOC ship with the LOC.

so does the e53 x5 need a loc?

I've been using the speaker level inputs on my amp for almost a year before I finally ran RCA's and installed my AVIC F90BT a few weeks ago. Tap the wires that are pointed out on the BSW website and give it a try, then decide. LOC's are like $5 on ebay, probably less.