Among the three I prefer the FH7. It has the blackest, deepest bass of all and a musical crispness in mids and treble. Most neutral tonal balance of the three (sans EQ). The SE846's bass also reaches deep down, it just doesn't provide exaclty the same authority and sounds slightly muddier. Mids and highs are clear and smooth, the treble is rather smooth than crisp, but I liked it from the start despite the arguable early drop-off, as it has an organic realism in it. The Andromeda is the sparkle king, the treble sounds very clear and extended, bordering on exaggeration, at least at the upper end. It's a distinct «high-end» sound which has found a lot of friends, also in myself, but I've begun to somewhat withdraw from it, as it isn't organic enough for my taste, not realistic (crisp) enough with some recordings, rather cool than warm. Midrange and bass are very clear and fast as well, but from ~120 Hz downward the amplitude response gently drops off. Not a big deal with a capable equalizer, but unfortunately my FiiO players' lowest EQ frequency band is 31 Hz, which makes for some handicap in comparison to the contenders. In terms of soundstage they are close: 1. Andromeda, 2. FH7, 3. SE846.
Now my above description refers to the sound with optimal equalizing. If you're not into it, I may not be a reliable source of information, as I'm not used to them in their raw factory state anymore. I guess the ranking would persist, although the (mid)bass-emphasized Atlas could be at risk.
Nevertheless, here's my subjective ranking:
1. FH7 + Atlas
2. Andromeda
3. SE846
The SE846 needs to be equipped with a better cable (e.g. FiiO LS-3.5D or ALO Reference 8) to get on a similar level (already respected in the ranking).
Norway winter here.Havent tried them outside yet ,but good to know they can handle it. 
