Ok, let me blow your mind a bit…
With Android 5.0, USB audio endpoints are “possible”. This means that if given enough power, an Android tablet or phone, could power an Explorer AND run Roon. Maybe with a powered USB hub, you can use multiple USB DACs on your Android device.
On Android, we’ve not enabled accepting incoming connections from other Roons running as remotes yet, nor do we support USB endpoints on Android 5 (yet!), but this is coming…
Just imagine a totally fanless solid state tablet or phone running your Roon “Core” in a year or two. The hardware will surely get fast enough. Newest phones/tablets are already quad/octo-core 1.7+Ghz ARM w/ 3gb ram. In 2 generations, they will probably beat today’s Core i5 NUC.