I have the FiiO E10K paired with the X1. It definitely sounds better than the on-board sound when you switch on the gain and bass boost. Without gain or bass boost, it sounds very similar to the onboard of my Asus Z97-AR.
My only complaint about the E10K with the X1 is that some songs that use an overabundance of auto-tune can sound "off" not bad, just, "off".
I can be listening to one song with heavy auto tune elements, and I'm like what is this? Then I switch to a song that doesn't use auto tune, or at least not as much as most pop songs, and the experience is nirvana. When I use onboard sound, these auto-tune heavy songs are not "off" but those songs that sound like nirvana, aren't quite what they used to be. The FiiO E10K is a decent match for the X1, but I do think it would be in your best interest to get something a little bit better, or something that potentially pairs better with the X1. I am very happy with my E10K and X1 combo, but I am confident that for around $120-$150, you could find something that provides better synergy.
Edited by Faceman - Yesterday at 9:45 pm