Zargon,
The ic's are in the motor controller circuit. I had a split platter Denon at one time; can't remember the model number, but the motor control cicuitry was in a separate box that connected to the table via an umbilical cord. Is that like your DP80? My DP55K has the electronics built into the underside of the plinth. Curiously, my table was back at Denon for repairs and needed a couple of ic's replaced. If anyone is interested I can provide the part numbers from the repair slip. Let me know.
Donshoemaker,
The DA307 arm was indeed capable of excellent performance. If my memory serves, it was part of a whole vibration control concept that extended from the tables platter mat to the development of the 103 series cartridges. It worked great with the 103D, and when they were not available, I found the Adcom XC-MRII worked very well. Your concerns about longevity are well founded. I ultimately wore mine out. An SME 309 now works in its place.