The Lightning DS App supports all iPad models only except and iPad first generation due to its IOS upgrade issue. However, AURALiC doesn't recommend iPad 2 / iPad mini first generation to run the Lightning DS App because the processors built in these two models are too weak to run the APP smoothly.
If you have a large music collection, you may need to get a flagship type for proper operation. Please refer to this article for detailed information.
iPad Air 2
iPad mini 2
iPad mini 3