Hello,... well, is not a 3X increase for sure, you can't compare like that. Rather let's do a good ol' car analogy. Say, if your computer motherboard is your dacia logan, the fiio e 10k would be a mercedes c classe and the aune x1s a bentley. All 3 get you from A to B, though all the road experience is different.
In my opinion, you don't need all the time an X1s, as it's an overkill.... like you won't drive to supermarket with a bentley unless you're an idiot of some sort. You will go either with the logan or the c classe and take the bentley out when you want something else... something higher tier and better experience.
Btw I'm not a fan of either of these cars, they just came out like that, you can replace any brand with a similar in the same class... say mitsubishi colt or nissan micra instead of logan, bmw series 3 or alfa romeo giulietta instead of mercedes C and some cadillac or spaceship enterprise instead of that bentley. Whatever you like... you can even replace the lower class with a barrel full of cabbage for example.
Now, back at it..... the aune x1s is ultimately better than the e10k, not 3x better.... but how you exactly quantify the difference between a mercedes c clase and a bentley continental ? Or a german sheppard and a wolf for that matter ? Is unquantifiable and any difference, small as it might be, is in fact infinite. But here the difference is obvious.
The X1s will give you more goose bumps, if you feed it with flac files, than an e10k. If you use it for gaming and ocasional listen..... an e10k is good enough, but if you want more and tend towards ultimate, then an x1s makes sense. The x1s is the wolkswagen phaeton, while the e10K is your fancy commuter bmw 3 series. Now you judge which one has more style and think of why the phaeton is 3x more the price.
The X1s is superior to fiio E10k when listening to high end music and well recorded stuff, there is no comparison there. But if you feed them both with mp3's the difference won't be that big. If you listen to youtube, the same, no that big of a difference ! If you play games with it, the same, you don;t need the x1s for that, the E10k is enough.
So, back at cars stuff.... you need several of them to cover all purposes, ideally all the 3 classes i mentioned above. But if you need just a practical one and some style, then the mercedes C class may be enough, like the fiio. Otherwise, the x1s is always the better, though you will only hear the big difference if you properly use it. The e10k will stop sounding better at some point, after youtube and ordinary mp3 in best quality, you will see a small improvement in flac but if you put the same flac on x1s, it keeps scaling up and will improve your experience drastically as it will make your headphones shine brighter, make them do the sounds and ranges that the e10k can't do. Is all about that little more, those fine details for which you need those expensive headphones. The X1s will make them sound like they worth it.
So, hopefully you understood something. It took me some time and some money spent to get that properly :)
I basically use the E10k for gaming, internet listening, youtube, carry around... as general purpose and the X1s when wanna really listen to some music. I hope that makes sense, that in my opinion, you need both or some sort of a similar setup.