Well, the Amp3 is the best sounding DAP I own, all things considered. As noted, the hiss with the UM3X is still there, but soon to be gone (I hope) via firmware. Amp3/Grados is fantastic. Also, the Fuze/LOD/Amp3 combo with Grados is also excellent (though too much hardware for portable listening for me).
Oh, I sold my PAA-1 buds, because my ears just can't tolerate buds for more than 30 minutes. They cause pain. Just a fit issue. Same thing happened with the Yuins, which I sold as well.
The Clip SQ is the Clip SQ, very good to my ears, but not better than the Amp3. However, with decent rips and the micro card, having 23+ GB of music on that little thing just amazes me, so I am using it as my daily dog walk DAP permanently (permanentl for now, LOL). I use the Amp3 at home, with the Grados. When the hiss issue disappears, who knows?
Seems maybe the Fuze is gonna be on the FS forum, not sure, since the Clip+ can also play flac files (as will the Amp3 after firmware update).
A good HF friend says the Clip SQ isn't as good as the Fuze, but I think they have the same basic innards on that front, so not sure why he feels that way. I can't really tell the difference using the same rips/tracks.