Well, I'm not sure if AP1 cars are affected, I think they are, but the USB music might be a good idea - streaming is practically unusable at the moment: constant buffering and connection errors.
AP1 cars are affected, I have an AP1 MX as a loaner and has the same Slacker buffering and connection issues as both my AP2 S and X. Some days / hours it's OK, others unusable.