[turzol]

Hi,
I've got a basic sound setup in my E91 2006 without tweeters in front doors.
Recently I've bought 2nd hand i-sotec 4channel amp to add some juice to the stock speakers.
That amp is plug&play meaning it's plugged via ISO adapter to 40pin quadlock connector.
I've connected the amplifier correctly to my installation, it indicates operation with a green diode when gets powered but there is no sound coming from the speakers.
Does it mean that I need to recode my HU in order to get this working?

I connected to the ground (black cable) and the yellow +12V cable coming out of the quadlock.