Audio Systems: Issues with replacement radio in E46, high performance system, 2003 bmw 325i

Question
My car: 2001 BMW 325i –
Last 7 digits of Chassis / VIN # FT25871

Car came with Premium Harmon Kardon Sound system. The radio got damaged and I was told to replace it by the local dealer.

Original Radio:
BMW Professional RDS  -  65.12-6 902 709

Replacement Radio
I bought a radio on ebay with the following description:

BMW 6512-6 921  963 model AM/FM Radio  
This unit is BMW model  6512-6 921  963 AM/FM Radio and CD player. It has 12 fm and 6 am programmable stations and a single disc CD Player. A CD changer can be added. It is an official BMW product from 2003 BMW 325i. No security code is needed to turn it on. Just plug  and play.
 


This radio fits fine in the car, it connects to the factory harness and it works with the steering wheel controls and it works with the CD changer in the trunk just fine.

Problem:
1)   There is no antenna connection on this head unit similar to the one on the old head unit, so the ‘radio’ section  does not work so well anymore.

2)   The “high performance” system does not sound so high performance any more – little to no bass.

Help !!

Answer
The thing is, you are mixing two different years, and two different premium audio systems. The HK componets usually are incompatible with the other systems. I'm surprised it works at all! You have two choices, get the EXACT replacement BMW headunit, part number and all, or have a stereo shop replace with a nice aftermarket unit, that either integrates with the HK system, or bypasses it.