Just got an Apogee Groove.
It works with my Samsung Note 4 (T-Mobile with Android 4.4.4) without a battery + usb cable splitter adapter.
The Groove's built in amp is pretty terrible, at least with IEM's like my JH Audio Layla. The sound is heavily veiled, almost muffled sounding, with the soundstage and imaging really smeared. It's basically like putting cotton balls in your ears. Using the headphone out from the Groove to my Pico Power greatly improves the sound. So perhaps the Groove does not play nice with multi balanced armatures like in custom IEM's.
I also dislike that Windows drivers are not available without registering. I question the legality of such a maneuver, as it limits the functionality of their product; and (at least in California) registering a product is not required for full warranty coverage claims. Not having a driver for a product is basically not delivering a complete product as advertised.
I don't see the point of them limiting the release of Windows drivers, other than to limit 2nd hand sales of their Groove.