Trying to upgrade standard sound system in an 04 E53 3.0 to DSP. Have a Loewe DSP amp from a 2000 7 Series, an 04 DSP Subwoofer enclosure and a DSP MID. The Loewe amp has round pins and the stock harness pins are flat. Anyone out there have any gouge on how to rig all this up? Plug and play is a bit of a reach.