It is XM or Sirus compatable you can use either...it says it right on the product features....I don't know why they are telling you no, unless they do not have the right experience...you need to tell them that there is a harness and you have a face plate, one could use the amps to power a sub becuase while it have 30% more power if you do not have premium sound you will want a little pop out of it.