You asked so here it is. I just posted this in the DX90 impressions forum.
 
 
 
So I just got my DX90 and did a quick comparison to my X5. All I can say is wow for both. I think that I would be happy with either, but they are different enough that I will be happy with both. Here are some quick impressions:
 

1. Soundstage: I feel like the DX90 is bigger and the X5 is a little more intimate. The DX90 feels airy like it is in a concert hall while the X5 has a very black background, more like a studio recording with everyone in a different sound booth. Neither is superior, just different signatures.
2. Volume: I feel like I need to turn the DX90 up to get to the intimate “in the living room” soundstage which it does effortlessly and without getting shouty at higher volumes. For my NT6pro CIEMs I have the DX90 comfortably at high gain at 170, which would have killed me on my DX50. On the other hand, I do not have to turn up the X5 nearly as much to get to my preferred intimate soundstage.  However, the X5 can get brighter and shouty when turned up to higher volumes depending on the song. Both work well and sound great, so neither is superior, just different.
3. Texture: After turning up the volume to get to the appropriate intimate soundstage for my listening preference, I am all about texture. They both excel in layering texture that I couldn’t even hear before on a portable source. I thought this was restricted to my balanced Mjolnir/LCD2 setup, but no longer. Both not only express the texture that is front and center, but separate individual textures from each sound source are well represented as well. Here there is a difference. While I hear the textures equally with both, the X5 allows me to really feel them with its more intimate presentation. The DX90 sounds great, but the sounds feel further away, not hitting me in the chest. I’m not saying that the X5 takes a win here for everyone as the DX90 is more euphoric which is very compelling as well.
4. Signature: While both are very neutral signatures, the X5 excels at intimacy, black background, and texture that you can feel as well as hear. Where the DX90 excels is in opening up the soundstage and creating a very euphoric listening environment.
5. Detail: Both are equally great at generating detail but do it differently. X5 detail is more in your face and supported by a very black background while the DX90 seems to layer it very naturally. With the DX50, sounds got in the way of each other and covered up if behind each other in the same blob. This is not the case with the DX90 where you can distinctly hear two different guitarists in the same area.
6. Power: While I would not use an external amp with either, the X5 feels more powerful and like it has more reserves to support dynamics. The DX90 eliminates the clipping problem that the DX50 had with dynamic songs, but doesn’t sound as full and ampy as the X5. The X5 bass and other big sounds come full on, full size, and natural where the DX90 is a little less full and maybe a little tinny (without clipping) at times. That is not to say that the DX90 doesn’t have slam – it does – but the X5 outclasses it here for those that insist on stacking for power.

 
Just a few initial thoughts, but remember there has been zero DAP nor Brain burn in so my opinion may change latter. Now it is time for me to disappear like everyone else that got theirs and just enjoy.   

Thanks for making this even harder to pick, lol. I think I may lean to fiio as I really enjoy the black background in music, which is what I loved about the ck4 I had. Plus $75 cheaper....thx for ur thoughts

Thanks barra....i think x5 will suit my taste...i own x3 so do you think it's worth to upgrade to x5..SQ and price wise?

bonve said:

Thanks barra....i think x5 will suit my taste...i own x3 so do you think it's worth to upgrade to x5..SQ and price wise?

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Never heard the X3 to compare, but from my reading, I have only heard one person that preferred the X3 to the X5 due to the X3's much warmer signature. Otherwise, what i am reading is a pretty unanimous preference for X3 owners to upgrade. The X5 is very neutral with a black background that would be impossible in a warmer signature. It is the black background that drives the X5's separation and generous details. What gets me with X5 is its very full sized sound and powerful dynamics that give it the 3D texture that I can actually feel. 

Yes i feel x3 is too warm for me...it's fun and very enjoyable though. .maybe because my iem se846 is already in warm side..i heard se846 with x5 is best combination. ..thanks for the review..i am sure i will get x5 soon

Thanks for the report as I now think the X5 is the way to go for me.

I will be very interested in your findings when using the HD 650 headphones as I find they sound great no matter what type of music is played

Went to a pro audio shop to compare both players today. I used the Philips Fidelio S2 IEM for the audition. In my brief 1 hour audition, my general impression is that the X5 is the more neutral player of the two whereas the DX90 is more tilted towards the low end - the sub-bass and mids are more obvious with the DX90 on the same tracks listened to on the X5 (the DX90 managed to somehow make my Fidelio S2 produce awesome bass! not that it usually doesn't, but usually the bass is not especially pronounced on the S2). Highs on the X5 sounds brighter whereas highs on the DX90 sound warmer and smoother - e.g. the sound of a solo violin is much smoother on the DX90 and could sometimes sound too bright on the X5. Therefore, I feel that the X5 is a more neutral sounding DAP which some might actually find 'boring' whereas the DX90 is a slightly colored and more fun sounding DAP.
 
Soundstage wise, the DX90 sounds slightly wider than the X5.
 
Details wise, I think both are on-par and just present details differently as mentioned by others previously in this thread or the X5/DX90 threads.
 
Dynamic range wise, I was quite impressed with the DX90 as it could present pianissimo as well as fortissimo passages in classical orchestral music very dynamically - so, soft can be very soft and loud can be very loud! And when it gets loud, the music isn't in your face and is actually very much like the climax during an orchestral concert, just AMAZING. The X5 I feel, doesn't have as wide a dynamic range, it is perhaps slightly smaller. (I listened to the 5th movement of Bela Bartok's concerto for orchestra to compare the dynamic ranges of both players.)
 
User interface wise, I think the DX90 wins almost hands down. The touch screen makes navigating between songs, folders and menus much quicker and convenient. The scroll wheel on the X5 I feel, is often hard to control precisely because I easily OVER scroll beyond my intended selection. However, that being said, I feel that being able to control the volume with the scroll wheel on the X5 is more convenient than just the buttons that we have on the DX90 (you can't control the volume on the screen even when you have pressed the volume buttons and the meter appears on the screen).
 
Conclusion: I'm getting the DX90! I choose it over the X5 mainly because of the UI which I find much more convenient, the fun sound signature, wider soundstage and the great dynamic range (wow!). I've preordered it in a local shop and should get it in a week or two. I'm very excited!  

As I just mentioned on the DX90 thread:

At this level of performance we are probably talking "horses for courses" with signature preferences and HP pairing being the most important aspects. I tend to think of this crowd in terms of the AK's being the shallow beauty queens with the 120 being much hotter, the X5 being the highly skilled star quarterback with brute force, and the DX90 being the popular, highly talented rich kid with all the toys who is very fun to hang out with. At a high school party, you would want all of them to show up.

For my purposes, I have both the X5 and the DX90 as they serve different purposes.

barra said:

As I just mentioned on the DX90 thread:

At this level of performance we are probably talking "horses for courses" with signature preferences and HP pairing being the most important aspects. I tend to think of this crowd in terms of the AK's being the shallow beauty queens with the 120 being much hotter, the X5 being the highly skilled star quarterback with brute force, and the DX90 being the popular, highly talented rich kid with all the toys who is very fun to hang out with. At a high school party, you would want all of them to show up.

For my purposes, I have both the X5 and the DX90 as they serve different purposes.

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Great analogy! So I guess you can start that high school party anytime now! 
 
Anyway, who knows, I might decide to get the X5 too later.. (and there goes my wallet! )
 
I guess it's just that the DX90 has managed to attract me first. 

Where is all the Google reviews between these daps ? Some off us is still waiting to buy. Please help

Does anyone know how these players sound vs an iMod/Diymod?

My sentim

classicalviola said:

Great analogy! So I guess you can start that high school party anytime now! 

Anyway, who knows, I might decide to get the X5 too later.. (and there goes my wallet! )

I guess it's just that the DX90 has managed to attract me first. :basshead:

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My sentiments exactly! I can't decide on either as both are good in their way. Getting the dx90 first, and maybe the x5 in a months time, if I can afford!

I think the DX90 might just edge sound quality but they have both exceeded my expectations. My DX90 though shows 'scan card' screen every time I turn on, misses the last two seconds of songs and sometimes needs two goes to play a DSD. The X5 performs faultlessly and battery lasts longer. So if I could only keep one it would be Fiio at present.

andrewh13 said:

I think the DX90 might just edge sound quality but they have both exceeded my expectations. My DX90 though shows 'scan card' screen every time I turn on, misses the last two seconds of songs and sometimes needs two goes to play a DSD. The X5 performs faultlessly and battery lasts longer. So if I could only keep one it would be Fiio at present.

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Have you tried a factory reset on your DX90? It might solve the scan card problem.
 
As for missing the last two seconds of songs, have you turned gapless mode ON? And does it still occur even after gapless is ON?
 
About the battery life, it's true that the X5 last at least 3-4 hours longer, but the upside is that the DX90 will be more environmental friendly in the long run since the battery is user replaceable. This also means that with several fully pre-charged spare batteries, you can just swap the currently flat battery in the DX90 with a new fully charged one and you're ready to continue enjoying your music without having to put it aside for charging.
 
Just my two cents.