Can I ask why you are asking? Are you spec'ing some aftermarket audio equip (like a 6-disc CD changer) that this applies to?
If it is a CD changer you are wondering about, the answer is no, no DSP. Some 5-series a few years back had a special DSP audio input on the amplifier that requires a different interface adapter for a CD changer.
If your question just asks if we have DSP in our system, the answer is yes. The little speaker button on your dash engages DSP to enhance the sound if desired.
Hope this helps.