With a phablet or tablet you can as well try USB Audio. Both versions of the M8 support USB input.
Here's a post where a head-fier DanBa updates a list of compatible sources and USB DACs every 5 pages (I think the M8 is already confirmed).
Mind that USB Audio support by Android is still rudimentary. The only way to stream hi-res digital through USB for now is an app called USB Audio Recorder Pro, and it's UI is pretty basic since it's never was supposed to be a music player. It's author was working on making a system service that would let other players use it to stream 24/192, but nobody knows when it's finished and when the likes of Neutron and PowerAmp will support it.