Guitar Hero: World Tour's recent launch saw boxes of plastic instruments flying off store shelves, quickly selling out in many areas. Unfortunately, many players reported problems with the bundled drums sets, prompting Activision to release a drum "tuning" application and a free midi-USB cable to connect the instruments to a PC. Otherwise, reviews for the game have been largely positive, and MTV's Multiplayer Blog did an analysis of using Rock Band drums in GH:WT, and vice-versa. Kotaku looked at which set was louder, coming to the conclusion that while they sound different, decibel levels are very similar. The early success in sales for GH:WT caused Activision to say holiday demand may not be met, and that they're examining two methods in particular to develop the franchise: instrument upgrades (hopefully less ludicrous than Logitech's $250 axe) and the possibility of a subscription-based model for user-generated content. "[Activision Blizzard CEO Bobby] Kotick says that there are now 25,000 user generated tunes that have been created for the game, and projected 'up to 100,000 songs' by the end of this year."