Zumo 665 as XM receiver off-bike?
I'm getting a new R1200RT (without radio) and would like to get a Sirius/XM subscription but from a single subscription I'd like to use it in my other two cars and at home via boombox. The other two cars and boom box have 1/8" inputs so in theory I could just pipe the music out of the Zumo 665 to them, right? Is the XM antenna build into the 665 or separate? I imagine satellite visibility could be the problem at home so on second thought I'd probably just use the internet option at $3.50 per month for that.
Just wondering if I should go with the 665 or a non-XM GPS like the 660 and just get one of SiriusXM's little gizmo boxes for reception, but then that's another gadget to find a spot for and coordinate bluetooth pairing etc with, whereas a lot of it is already in the 665.
So I guess I'm really wondering about the feasibility of using it like that, how the antenna is placed, and of course wondering if Garmin will come out with a new, better model soon, before I invest this much $$ into a GPS! Thanks in advance for any help.