The iPad is just the interface. You could pretty much use anything but a phone is going to be more one-handed and convenient. The newer the better and that is just for efficiency, but you must have a Core device in your home in order to use Roon. A Core device is a computer, Mac, Windows that is stable and always on. So, you may think a laptop but as soon as you close the lid it will turn off. Sure, you could go into settings and have it not go to sleep when you close the lid... but just don't. I mean if this is your only option, sure, but I recommend you either buy a Roon Nucleus to give you the best experience or load Roon Rock on a dedicated Intel NUC. https://help.roonlabs.com/portal/en/kb/articles/roon-optimized-core-kit