I would prefer to add XM rather than Sirius. Is there an XM model compatible with the '07's? Where the models discussed on other forums seem to require 4 cable connections, my bundle has three, including a slightly different male end for the optical cable.

See Clair Parts web site for more specifics. Apparently 2007's take a modified Sirius tuner relative to 2004's throgh 2006's. Clair says there is a VIN split at 10000+ even within 2007 for yet another variant. I'm guessing somewhere in this cutover is where the cable variations occur. I might also speculate this change occurs at the point they cut in the Audi Music Interface (AMI) into 2007's. Feels like it might be bad news trying to retrofit an XM from the earlier years into a 2007.

The prior owner did switch the Sirius in my 2006 as it was delivered new to an XM after a few months (done at a dealer). XM unit seems to work just fine. I saw an XM unit (the MMI/nav compatible type--the part #'s starting "4E0...") on e bay the other day that sold sub $100, so if you can pick one up cheap enough used you might want to roll the dice, then resell it if it's a bust.

since I have 3 other XM radios. Since my post, I've found a splitter from TERK that seems to solve the 2 vs. 1 antenna lead problem. Unfortunately I am in the later VIN# group, and its the antenna leads AND the optical connector which have changed. 4E0 is right, but it seems that an "H-type" tuner is now needed, and I haven't found an XM tuner of this type. The frustrating thing is that it probably wouldn't take much to fabricate a piece converts the old male lead optical to the new female tuner receptacle, but I doubt there would be much demand for it.