Just to confirm, there was a problem with the early sirius tuner's passthrough port. I had that unit with my keg, and about once a week I would have to unplug the keg and plug it back in for the headunit to recognize it.
The new sirius unit's passthrough works fine (except in my case, where I have the switching unit & and sirius tuner in a failed attempt to make the Keg, Sirius, & iPod adapter all work).