As to the XM direct TV question the feed is perfectly suitable for background and party music. Also the quality of XM from Direct TV is noticeably better than the XM tuner I tried. That said It cannot compare with good FM.
To chime in on your Mac tuner question (I currently own a 1500 receiver, two MR74's and two MR73's and have owned an MR78) I won't disagree with the MR71 being the best sounding as I have not had one to listen to long term (and the 1500 receiver is supposed to be the MR67 eqiv)but The MR74 is easily the best combination of sound and signal capture. Audio wise it is the reason I sold the MR78 and to my ear it is better than the MR77 as well. Also it usually sells for about the same as an MR77. I paid around $400 for both of mine on eBay plus about $150 for a alignment/tune-up from Terry DeWick.
To chime in on your Mac tuner question (I currently own a 1500 receiver, two MR74's and two MR73's and have owned an MR78) I won't disagree with the MR71 being the best sounding as I have not had one to listen to long term (and the 1500 receiver is supposed to be the MR67 eqiv)but The MR74 is easily the best combination of sound and signal capture. Audio wise it is the reason I sold the MR78 and to my ear it is better than the MR77 as well. Also it usually sells for about the same as an MR77. I paid around $400 for both of mine on eBay plus about $150 for a alignment/tune-up from Terry DeWick.