Been listening to the Pistons, use X3 into ALO National (line out), don't have a problem with the sound this way, very nice imo, haven't tried it straignt into the X3 (mostly use it with the National, I think mostly to justify having bought it, LOL). I do think the amp in the X3 is its weak point, and like bypassing it-sounds heaveny this way (as per earlier discussion-I do believe any DAP that can drive headphones, including phones, have to have some sort of amp. The quality can be really poor, but it needs to generate some current to drive things). Have a new set of Gratitudes, still in the box, don't have the Havi, maybe I need it, who knows? Get around to breaking in the replacement Gratitudes soon.
The Piston case/box does drive me nuts, too, feel you need an engineering degree to put it away!