Ice-Link DSP Converter and 3 and 6 pin cable install

[Acezoned]

Ok, here is goes. I have 2005 X5 with DSP and Nav and Ice Link Plus. All is working but I'm wondering if Al and Ed's took me for a Digital Signal converter and some wiring explanations. I had to take out the Icelink to get it fixed by Dension (firmware issue and they were great) they also turned me on to a new cable that went straight from Icelink to 3 and 6 pin cd changer port. The other cable was coax and had converter on end for 3 and 6 pins to what would be cd changer port. When I purchased this I saw them carrying and was charged for a Radio Shack Digital Signal converter. I now do not see it and based on on the Dension Install supplement for the Ice link it says cars with 3 and 6 pin connecters can use standard BMW install kit and not the Dension BMW DSP kit (?). It makes reference to "true" DSP will have cable coax but then says the bit about 3 and 6 pin, which I assume is newer.
Why wouldn't I need the Radio Shack device? The DSP is working fine with Ipod but am I missing something here? What's the difference between DSP with 3/6 pin and coax? Many thanks, Ace.