Hello....I currently have a HR23 receiver and I want to get upgrade to a HR34. I have a dish with one wire coming out of it and it goes through a little plugged in device with a single wire going into the HR23. My question is will upgrading involve just taking the one cable from the HR23 and screwing into the HR 34? If not, how hard is the work? Also, if I don't get my local channels from Directv..will an AM 21 work with this? There is a reason I asking....thanks.