Hi all, first time poster so be gentle. I have a 2003 A4 with a Symphony 2 and bose rear amplified. Im currently attemping to put a single DIN Sony head unit in. I have the converter lead with pre-outs to fit straight into the Sony. My problem is, when checking the 12v ignition source I get 11v when on and 0v when ignition off (so far so good). But when I connect the ignition source to the Sony, the voltage drops down to near as nothing and the HU doesnt function correctly. Shall I just tap into another switched 12v and use that? If so, where shall I take it from? Thanks!