Not long ago I saw an advert that was maybe a couple of minutes long that featured a mobile app that functioned as a guitar amp by listening to the notes played on a guitar it was near or attached to and played the appropriate sound. The advert consisted of a number of guitarists trying the app out and making some commentary about it, like commenting on the fact that they can just walk around with it and not be constrained by cables. If anyone knows of the name of the app in question it would be much appreciated. If you need any more information for a lead i'll do my best to provide what i can remember of the advert.