Need help choosing radio

Hi Folks,
I am considering a Sirius radio for my car but I need one that has a volume control on it or one that comes with a remote control that has volume. The reason I need this is because the volume on my (very expensive to replace) car radio is screwy so I have it set to super-loud and use the volume on my attached ipod classic to control overall volume. I spoke with Sirius tech support and they say the only way I can do it is to purchase a home receiver that comes with a remote (Onyx model number XDNX1H1) and a car kit.

I am curious if anyone knows if this way will actually work or of a different way to achieve this.
Many thanks,
Chris

Does your very expensive car radio have a sat option? Why not hook into the factory radio rather than plugging in an add on?