Auralic, which used generation or model IPad works with Auralic app

I have a Auralic G1 and a Aries Femto clock and have been using my I phone but would like to use an iPad. I have an older iPad that is to old to work with the Auralic app. I've never felt the need to buy a new iPad because I use a Mac laptop. I will only use this iPad for streaming. I would like to buy used. Can I buy a used iPad that will work with Auralic app and if so which one or how far back can I go to save money. I called Auralic but they couldn't answer the questions just told me to buy a brand new one. Thanks for any advice.