Brunz

Question… about taping into rear speakers for a sub...

I have been searching through the Audio forum about adding sub & amp.
I have experience with car stereo installs but not with existing systems.(like BOSE)

Some posts say "You need a line converter" for the amps to sound right.
Makes sense if you where taping into wires coming from BOSE Amp.
Other posts say "You do not need a line converter"…
Makes sense if you where taping into wires going to BOSE Amp.

So here is my question….

Which way is the proper way to do this and get good sound…
(or the best you can do with a factory deck)
Line Converter? Or tap into wires from the HU?

help me out guys??

TwentyValveB5+S4

otherwise, you'll add a lot of noise.