My FiiO X7mkII probably isn't much of a bottleneck, so investing in a more expensive cable to use with my favorite earphones could be interesting. My spiral dots have been serving me well for the earphones I have, but I would like to try some Shure olives style tips on them some time, because they isolate to well, I really liked them with my ER4. A-B-ing between cables it a bit tricky if you don't have two pairs of earphones that sound exactly the same. By the time you swapped the cable and have the phones back into your ears it is difficult to compare the sound to what you heard minutes ago. Now that I have received some more balanced cables, I've been listening to my other earphones again. There's something that makes the AS10 so pleasant to listen to. The sound is full and tight because of the BA drivers, with nice texture. Quite forgiving and non-fatiguing. I has a pleasant warmth to the sound and doesn't seem to have any annoying spikes or dips in the spectrum. It sounds pretty smooth, I would describe it as organic, analog sounding. Very good for music with lots of atmosphere, the Stranger Things synth OST sounds really good on it. There's the treble roll-off, the soundstage is very small, instrument separation is okay. Somehow when I try them I don't feel like taking them out again.