I kind of (read: completely) skimmed your post when I saw what you were asking, so it’s entirely my fault that I failed to spot that you’d already listened to “a wide range of music through both”; sorry.
Still, and to add to my edit, unless you’re assured of the quality of your downlaods, I’d be inclined to go back with CDs or of some carefully selected songs, preferably ones that you know quite well. MP3 quality tends to be mediocre at best, and I’d want to know that any problems in playback aren’t limitations of the format/download, rather than of the media.
After that, it still comes back to my first post. Just get as long as you can in the listening room. If you can’t discern between the two, it probably doesn’t matter if somebody else says they can.