Just to let people know. This achievement doesn't need to be done consecutively. You do need to get 15 consecutive wins with the controller but if you lose after 10 wins or something you will still obtain the achievement on your 15th win. The only way you can miss out on this is if you connect your guitar and then lose a song, this will break your streak and you will therefore have to start again from 0. I found the best way to do this was to host a ranked face off match with only 1 song, pick the easy difficulty and then choose Missisipi Queen. This song is very short and simple so you shouldn't have a problem.
Good luck and just make sure you get the achievement before playing online with your guitar again.