Here's my short bit if impressions about the X5 and some comparison with the DX50, both of which were shortly auditioned by me at a local audio store using my JH13FP:
Regarding build quality, the X5 felt fantastic in my hand. Its weight, while actually was a bit more than I initially expected, inspired a lot of confidence along with the brushed aluminium body. The wheel was not as rigid as I thought and while it might be seen as the weakest bit of the design, was really solid and I'd imagine it'd be easy to replace should problems occur. In contrast to some of the reports I've read here, the wheel's mechanism was precise and I had no problems navigating my way around. On top of that, the screen was probably the most vibrant of all the DAPs I've tried and it came at just the right size. However, if I were to suggest something to FiiO, I'd probably ask them to replace the plasticky buttons with something more durable and elegant-looking, but that might just be me.
The UI of the X5 was the best one I've come across so far compared to all the boutique Chinese DAPs I've tried and owned before. Full stop. It still hasn't reached Apple-level of refinement and convenience, but it's getting very close there and to me, it's thrilling to know that the UI is going to get even better with continuous support from FiiO. As mentioned above, the wheeling mechanism was very precise and worked flawlessly at least in the 30 minutes I was auditioning it. Choosing songs, jumping from one to another of even reaching anywhere in a 500 track playlist were a breeze, something I could only dream of while using my good old Studio V. The four directional buttons also proved to be of tremendous help with using the player and I experienced no lagging issues with them. I still want the buttons to be labelled properly though, though as an user has mentioned in the subsequent upgrades Fiio may give users the freedom to map functions into buttons to their likings, in which case there is really no need to do so. In comparison to this, the DX50's UI was a nightmare to use, though please take a bag of sand here as I did not have a look at the firmware version and thus had no idea which version it was at. The screen was ridiculously sensitive at the start of the audition, leading to the fact that each time I wanted to scroll the playlist down, I actually ended up picking a song instead. Things only improved a bit after I turned the screen off and fired it up again, but the problem still persisted occasionally. In addition to this, despite the lengthy time it took at the start, it seemed like the player did an incomplete job of scanning my SD card as each time I moved to a different folder or section of the playlist a message popped up informing me that a scan was going to be performed. This proved to be extremely infuriating especially when you're navigating your way in a large playlist and you get something like that once per five seconds. The physical buttons on the other hand were much nicer and I love how they are nicely separated and labelled from each other, most definitely a saving grace to the otherwise disastrous screen. However, I know that there are a lot of problems associated with changing or improving the UI of a DAP especially with small Chinese DAP manufacturers and in that regard, I want to give FiiO a huge pat in the back for what they've achieved with the X5 and for how they've always been listening to their customers to make things turn out the way they are.
Sound quality is probably the part when I feel the least confident about, taking into account the audition was fairly short (30 mins with both the X5 and the DX50) to give out any reliable impression but here goes anyway. Not surprisingly, the DX50's sound quality inspired a lot more enthusiasm than its UI did. The overall impression was that it sounded slight warm to my ears, with good detail and soundstage, but lacked a bit of extension on both ends of the spectrum with some slightly hazy imaging. Overall, it was a slight step up from my Clip+ especially in the soundstage department, but not good enough to convince me to shell out the money for it. The X5 was a different story. It felt powerful. The X5 spotted to me what seemed to be missing from the DX50: a more neutral response, more "resolution" in the notes, better extension in the bass region, more energy in the treble and an overall a more accurate and spacious presentation. Now you might say that this comparison is utter nonsense since I'm comparing a $239 player with something that is nearly one and a half time more expensive and I'd say you're probably correct. What I want to imply here is that most of the improvements mentioned above IMO may be the result of better amplification integrated in the X5, and what I mean by that is that to my ears, the DX50 while had more than enough power to drive the JH13's drivers to deafening volume level, actually did it with much less authority and refinement compared to the X5 (the gain was at high, btw). What this translates to is that IMO, you can close the performance gap between both players by adding a good external portable amplifier to the DX50 at the expenses of extra bulks and money (I'd imagine you have to pay some seriously good money for it though) and this goes to show you how incredible a bargain the X5 is. Throwing in the very solid and refined UI, better battery life and I have no doubts that the X5 has the capability to challenge (or even beat) some much more expensive DAPs on the market, given that I found the performance better than that of the Studio V and approaching the DX100's.
Lastly, I think I need to mention that by comparing the X5 to the DX50, I am not trying to say that the DX50 is a terrible offering from Ibasso, I found the form factor to be really good, the sound quality up to par and if they could improve the UI, it would no doubt be a solid buy. And if I hadn't heard the X5, the DX50 would definitely be on my radar. What is troubling me now is that I'm finding myself hopelessly smitten with the X5, its sound quality and its UI while not being able to afford it (yet!). Yet I'm still hesitating in forking out my precious hard-earned money because if FiiO continues this trend, who knows how much potential the X7 would hold. One thing I know though, I might just give up my cash very soon.
(Thank you to you guys who have the patience to read through all of this. It was meant to be a short impression but turned out much longer than I planned it to be).