If anyone is interested, I have the following equipment for sale to do almost a complete stereo upgrade.
Blaupunkt THA-555 PnP 5 channel amplifier
2 Earthquake Sound SWS-8x Subwoofer
Blaupunkt Adapter cable THA/PnP (Part #: 7 607 622 016-001)
Blaupunkt Connection cable THA/PnP 5.5m (Part #: 7 607 622 011-001)
$500 + shipping for all items. All items are brand new and have never been installed or used. I bought them and decided to not do an upgrade in my e90.
Let me know if you are interested.