I've recently got myself a 1998 A4 B5 which has the standard (non-Bose) factory sound system with the Concert headunit. I like the look of the unit in the dash, but unfortunately it is lacking in connectivity to plug in USBs or even just aux connections. For now I have a tape-line in convertor but it sounds pretty bad, and only comes out of the right channel. I considered getting a Connects2 adaptor but the head unit is past its best as well - the LCD display is bleeding and it suffers from the common volume problem, so if I were to go down the standard route I would need to invest in the Connects 2 and a replacement unit... I ideally want to get the best sound for as cheap as possible, so it makes no sense to keep it OEM. I've got a JVC spare headunit with a USB input, so I'm thinking of installing that instead and getting an ISO adaptor, but I have a couple of questions about this 1. Will the adaptor take into account the fact that VAG cars have swapped ign live and perm live? Or will I need to switch the wires over? 2. My rear speakers don't work - I think this is because the rear amp is either missing or not plugged in. There is a blue plug dangling from near the left-front of the parcel shelf. I have read that it is better to power the rears from the HU anyway (the JVC is supposedly 4x50). Do adaptor leads usually take into account that a rear amp is used? How easy is it to run some new cables from the HU? Where do I splice into? 3. I'm not sure whether the car has the factory sub or not - was this standard in the A4? If it is present, how do I wire that into an aftermarket HU?