For my main rig, which runs JRiver inside the computer, I use JRemote on the iPad and also on my Android phone. Just excellent, in my view.
For my travel I carry my phone and an iFi nano DAC. The phone connect to the nano thru USB and I use USB Audio Player Pro as the app to stream audio though the phone USB. It's ok. Not great, not bad. It's a bit quirky initializing the DAC at times, but sounds good.