I think the consensus will be the IPAD air 2 seems to work best.
I doubt you can get a 30 pin version, so your choices are either the DL conversion
Kit to change your 1608 to a lightning or buy the adaptor and lose the docking ability.
Caution, the foreign adapters don't work so well, I only have good luck with the real Apple
Adaptor.
Many people,leave the iPad 2 docked permanently and run the iPad Air as the wireless.