Hi JamesG; to play Rocksmith 2014 custom DLC you need this cracked .DLL file which allows customs to be played: https://dl.dropboxusercontent.com/u/26504831/RS2014/D3DX9_42.dll
Download this, place it in your Rocksmith2014 installation folder on your PC; and now you should be able to play Custom DLC. If it still doesn't work, then the author of the DLC just might need to re-package the file as the toolkit used still has its moments.
I just download this custom songs but I can't play them. This stuff is new for me. I put them in the dlc folder but I just get the preview. After chosing them I just get the amps background and nothing more, further more the game frozen up, what I'm doing wrong?