DICE install update, two more questions (99.5 Concert HU)
 

OK, in bright sunlight with a small flat screwdriver I was able to see what was going on with the radio clips, also thanks to a great explanation I found on vwvortex.com.

http://www.42draftdesigns.com/installation/tech/ddkeys.htm

Turns out that if you put the DIN keys in backward it bends the release tab outward. I pulled it back toward the center, then was able to get the DIN keys in correctly (slanted side IN, pointing toward the back corners of the radio, hear a faint click as the tab locks in, then move the keys outward toward the side which levers the clips inward and releases them.

Having the radio face plate off helps with this a lot (thanks MacSub) BUT, the face plate is held on with tiny plastic clips which lock into slots on the radio chassis. Even though I was super careful, some of them seem to have gotten "scraped" off and don't lock in anymore. This means that the volume, display, and buttons intermittently don't work. Pushing the face back in firmly works for a while, but I'm hoping for a more permanent fix.

The DICE module fit easily behind the CC unit (thanks broke90) and the ground and connectors were easy to install. I do have a small but annoying high-frequency whine now when using the iPod. Since I haven't changed any speakers I don't think it's the same problem as Pelican Pete had.

I'll have to take it apart one more time when my Panavise mount arrives. I'll either have to pop the face plate or take the radio out-ish to get to the 8mm bolt above the CC HU to mount the Panavise. Of the six little clips that hold my trim plate around the radio and CC, the two bottom corners have broken off. Hope I finish this before I run out of clips!

I'd reground the chassis of the HU to the bodywork of the car to get rid of whine

Re: I'd reground the chassis of the HU to the bodywork of the car to get rid of whine
 

What counts as the bodywork of the car? Any metal piece that's not the radio? The places where the CC controls bolt in? Those aluminum pieces under the knee bolsters? Since I'm going to have it apart again soon, I'll give it a try.

You need to try all of them and see what works, I recorded a "silent" track
 

then played that quite loud with the engine running so I could hear exactly what difference it made. Eventually found a point behind the glovebox that did the trick.

Re: You need to try all of them and see what works, I recorded a "silent" track
 

Just to be sure I understand -- this wire would come from the head unit/Dice ground on the back of the head unit to a solid metal part of the car, right?

Yes that's right, try and use a fairly chunky cable (8 or 12 guage), as short as possible