Check the listing for details. Amp Retention For Range Rover L322 DSP BMW 5 Series E39 Interface Control Module. Condition: New. Listed at 316.45 USD. This adaptor allows you to retain the factory fitted BMW DSP amplifier sound system in your BMW or Range Rover L322 when you are changing the factory radio to a new after-market head unit. This adaptor consists of a voltage regulator, audio circuits (inputs and outputs) circuits form a digital signal amplifier control and the control of the micro-controller. This device allows the exchange of the original Land Rover radio / navigation system to a third-party after-market product, therefor the Original Land Rover/BMW DSP amplifier remains in the vehicle and can be used with the new after-market head unit. Once you place an order with us, there is only a short time frame we are able to cancel that in due to the high metrics eBay sets for dispatch. eBay offers a service to request to "reque.