I've not tried it with bluetooth. There seems to me to be absolutely no point in squeezing high res music through a sonically destructive bluetooth connection. With WiFi, the signal path would be as follows:
Using the Mconnect app....
High res .FLAC file stored on phone is sent complete to 2go via WiFi at full resolution, which is decoded by Hugo 2.
High res .FLAC files stored on memory card in 2go are requested to be played directly to Hugo 2.
Music streams are requested by the phone over WiFi and sent directly and at full resolution from streaming service to 2go to Hugo 2.
For a wired connection, high res file or stream would go directly from your phone to the Hugo 2.
Using the Gofigure app, you can also play back music stored in memory card in 2go and also access internet radio (which sounds surprisingly OK).
Sorry, but I'm not familiar with the Apple airplay system, but the 2go manual gives details.
As for sound quality comparisons, I've never heard a Gryphon. It was on my shortlist. From what I have read, in reviews, the Gryphon and Mojo 2 offer a different but similarly detailed performance. My old setup was a DAP, a Shanling M6 (AKM edition) driving Quad ERA-1 headphones. These headphones seem to be very revealing of differences between sources. I liked the level of fine detail, nuance and fatigue free listening the Shanling offered, but it seemed to lack a bit of pace and weight driving low impedance planar headphones (and battery life was also short as a result). I tried the Mojo 2, and felt that I gained the weight and pace, I had ben looking for, and also had a beautifully fluid and organic sound. On the downside, I lost a little perceived detail and texture in higher frequencies and lost nuance and texture in the bass. Moving on to the Hugo 2, I got more weight and texture, better nuance, better high frequency detail than either previous setup, but still with the lovely organic fluid feel of the Mojo 2. These were not subtle differences needing hours of A/B listening tests to detect, more a punch in the face obvious move up the quality ladder.
Hope this helps!