Headfonics 2014

iBasso DX90 Review

One important note is this DX90 was tested with firmware, V2.0.0. 

Matured OS

iBasso played a smart one by not trying to throw out a brand new OS and GUI for the DX90. Given the fact they borrowed much from the DX50 in terms of physical appearance, it would only seem logical to throw in the same OS also given the amount of time the team has spent revising and upgrading it in the last year or so.

Those who care to remember the DX50 coming out with V1.0 will not have fond memories of multiple freezes, illogical menu flow and gimped cul de sacs when using the DX50 as their regular DAP. Many typical features seemed missing that should have been there during the initial launch.

Today we have version 2.0 and upwards and boy things are very different now with the OS on the DX90. With the DX90’s superior number-crunching power over the DX50 you a much more settled, mature and responsive OS.

With the DX90 it feels a little snappier, screens are loading faster and media is loading up in a jiffy. Gone are those irritating playback freezes, long media file scanning times are shorter and the lack of decent playlist support has been fixed. Whilst it is not quite Rockbox and I still think the X5 has a slightly deeper and more involving settings menu I do believe everything you need is right there now and most importantly it just works on the DX90 out of the box.

Some minor quibbles

The DX90 still boots up into the playback screen so you do still have to go from there to any sort of central menu system by either clicking My Music or Settings. I would honestly prefer if it booted up into one central menu and from there select your music or your settings.

Also given the rather shorter battery life on the DX90 I would still also like to see the battery shift from the far right to an omnipresent icon in the middle of the top row. As per the DX50 experience, it is really only on the playback screen that I can see if the DX90 battery is about to run out of juice.

Some new features since I last checked out the DX50

I am also super delighted iBasso actually added my beloved Genre – Artist – Album drill down library feature after much incessant nagging on the original DX50 firmware by my good self. I have been hankering after this feature in the new wave of DAP’s from FiiO and iBasso for about 2 years now and they finally agreed late last year to do it. There it is and it works great. If you have any issues check your tags as I only had one Null tag out of something like 2000 tracks loaded up on a MicroSD card.

File Management

Previously I would have a ton of Null files on the older OS versions. I also religiously tag my files so I do not have to rely on hard drive folder searches on large capacity memory cards so working a flat-file system like the X5 and DX50 was a bit of a pain. Working through the Genre system on the DX90 had zero pain and once all were scanned on initial loading everything felt pretty snappy. For those getting more than 1 or 2 Null files a “wipe and factory reset” should help to lower or get rid of the null orphan files. Once reset try the scan again to remove the Null files.


DSD compatibility of sorts is onboard also with the DX90. Whilst the DX90 Sabre32 DAC does not decode native DSD it will convert DSD to PCM 24/88 which is pretty darn good actually. Just make sure your files are using the DSF (Not DFF) extension rather than the native format. Korg Audiogate’s snappy conversion process is pretty handy also for converting to the DSF format and ensuring you have the right bitrates. As far as I am aware DSD64 is the highest level of bit depth you can use for the DX90 but correct me if I am wrong here.


The biggest talking point, apart from the sound quality, is what is under the hood of the DX90. The original DX50 sported a WM8740 24Bit DAC Chip implementation which is pretty much tried and tested now and perhaps getting past the sell-by date.

iBasso though did a fine job of wringing just about all they could out of the WM8740 and from our previous review we complimented it very highly indeed comparing it favorably to DAP’s almost double in price. For the DX90 iBasso ditched the DAC setup of the DX50 entirely and instead opted for a totally new dual-mono DAC implementation around the ESS Sabre32 ES9018K2M chip.

This is far more modern chip than the older WM8740. Tonally the ESS Sabre32 ES9018K2M has a far more dynamic, resolving and cleaner signature than the older, warm to neutral WM8740 chip.

Volume Control

Also volume control on the DX90 is probably among the best in the new daps I have tried to date outside of the AK series. The volume control on the DX90 is far tighter and more refined than the DX50 and a positive delight for IEM’s compared to HM-901 stepped attenuator.

The HM- 901 attenuator is pretty solid but the steps are much bigger for me on the HM-901 than the digital control on the DX90. IEM’s tend to crap out and distort pretty quickly on the HM-901 compared to the DX90’s more sensitive levels of output and s/n.

I rarely remember getting above 4-6 on the dial of the HM-901 with my least sensitive IEM’s compared to the oodles of play I got with the DX90. Forget about sound quality and which is better; if there is no control over the power then there is little point for me personally going with a higher-end unit for sensitive cans and IEM’s.


The DX90 exhibits a very neutral and transparent tonality and quite frankly it is a big step up from the DX50 making it sound somewhat dull in comparison. That is no slight on the DX50 which remains bang for the buck for me and superior to the FiiO X3 but side by side the DX90 is way above in terms of clarity and resolution. This is no sterile monitor like presentation either. The DX90’s attention to detail and fine image separation makes it a wonderfully engaging DAP also with superior dynamics to both the DX50 and FiiO’s own X5. The DX90’s soundstage is just so much more expansive than the DX50 and even bests the above-average X5 soundstage capability.


Bass on the DX90 is tight, hits hard and has more extension and texture/detail than the DX50 and certainly more attention-grabbing than the more intimate, thicker but slower X5 bass signature. Combined with my Merlins the DX90 bass response felt very firm and planted without any hint of fuzziness or bloom. This is the kind of clean bass I like with natural extension that doesn’t feel disjointed or lack coherence from the rest of the presentation.


The mids on the DX90 are relatively balanced with a very slight hint of warmth but with bit more bite and presence and not as sterile or cold as the original AK100. I wouldn’t describe the DX90 mids as being overly forward though. The large airy soundstage tends to leave a slightly less intimate experience with acoustics and vocals than the X5 is capable of. It is all about flavors really in that respect rather than any imagined weakness.


DX90’s treble is a thing of beauty with excellent control, articulation, and definition. It doesn’t sound blunted or recessed in anyway. There is certainly a lot more sparkle in the DX90’s treble presentation with a generally more airy feel than the X5’s more tapered top end.

It is a strange thing but when comparing to the X5, which I originally reviewed as being wonderfully smooth and coherent, I found it was the X5 which suffered from more sibilance than the DX90. This is despite the DX90’s treble being more forward and aggressive than the X5.

I often use Deadmau5’s “The Veldt” as a great reference track for sibilance checking. The tail end of the vocal can easily slip into a lingering “sssss” sibilance with any gear exhibiting slower decay and true enough the DX90 nailed this one and the X5 just slipped out one too many “s” in comparison.


Overall the DX90 sound is a major upgrade on the DX50 sonically and provides a worthy ying to the yang of the more intimate and thicker FiiO X5. My own personal preference tonally is the spacious, detailed and airy DX90.

The dynamic and clean tuning suits my tastes perfectly and gets the best out of my stubbornly warm and laid back UM Merlins which is always a good sign. I did take time though to run it through some of other IEM’s and a few headphones just to see what it could do both matching and power wise.

DX90 with the UM Merlins

Volume setting: 190-205 (low gain)

Ticking all the right boxes right here and putting some much welcome life into my otherwise warm and laid back UM Merlins. Whilst by no means magically turning it into a frost queen the UM Merlin’s seem more agile and responsive and the DX90 really testing that dynamic driver yielding some excellent, deep and detailed bass responses especially with EDM genres.

It is not all grunt and low end though with some wonderful agility and emotion combined with a proper display of the DX90’s imaging expertise with that fantastic soundstage capability of the Merlin.

DX90 with the UE900

Volume setting:205 – 220 (low gain)

Absolutely nailed it for orchestral flac, particularly “Evanstar” from the Lord of the Rings Two Towers OST. Incredibly detailed yet well controlled from top to bottom. The UE900’s slightly lighter application of bass and sense of roominess is an excellent match for the dynamic DX90 detail and imaging.

Solo female vocals are wonderfully detailed with plenty of emotion and not a hint of sibilance. The UE900 DX90 combination was a touch weaker with rock, in particular Bai Bang’s “Everybody Everywhere”.

Cymbal work felt a little harsh and peaky and the mids a little bit thinner I would have liked. The X5 did better in this instance outside of orchestral and EDM with a thicker bottom end and a more muted top end to control the lower treble splashiness on the UE900.

DX90 with the Fidue A83 (low gain)

Volume setting: 195-205

A relative newcomer to the market the Fidue A83 is a hybrid single dynamic and dual BA universal IEM. It looks darn sexy and retails for around $300.

I have only had these for a short period of time and using them with foams they still sound a touch brighter than the UE900 though incredibly detailed, fast and with decent bass extension. Using Daft Punk’s “Get Lucky”, I got a tremendous sense of speed with this combination but perhaps the A83 was a little thinner sounding and more distant and ethereal than the UE900 using the DX90.

DX90 with the Minerva Mi-Pro Artist (low gain)(CIEM)

Volume setting: 195-205

The Minerva Mi-Pro Artist is a 3-way BA custom IEM from the UK which I covered in early January 2014. Very natural mid’s, clean presentation and decent body added to a tight and snappy bass line. It lacks the bombastic feel of the UM Merlin but has a slightly more forward and intimate presentation that matched very well to the DX90’s panache for detail.

The multi-layered string work of Max Richter’s “Spring 1” from his recomposed Four Seasons work was remarkably accurate and energetic with the Mi-Pro. The UE900 though had a touch more clarity in the treble with the DX90 on orchestral works but that slightly muted lower treble on the Mi-Pro worked much better with the DX90 on rock.

DX90 with MrSpeakers Alpha Dogs

Volume setting:235-240 (high gain)

Sadly a failure with a tinny closed sound, squeezed treble and very low if nonexistent bass response. David Guetta’s thumping EDM Blade like “Glasgow” track sounded positively weak and lacking in any real depth, punch or slam. I should not be too surprised though because even the HM-901 needed to go to around 7-8 on the balanced card to really get the Alpha Dogs pumping so I didn’t really expect the DX90 to come even close.

DX90 with the Oppo PM1

Volume setting: 210-220 (high gain)

I was half expecting medium gain for the sensitive soul that is the PM-1 but in fact it really needed a high gain setting to get the most out of the PM-1 without the use of amplification. Probably the most efficient planer right now on the market with a consumer type presentation that really suits the DX90 in terms of control and getting the best out of that PM-1 top end.

The DX90 pushed the PM-1 treble in the right direction without a hint of harshness. Rock sounded pretty good with the DX90 and PM-1. That splashy lower treble was under much better control unlike the UE900 and the Fidue A83. I did feel that thick and lush signature on the PM-1 was a bit thinner than I would have hoped for but overall not the worst match in the world. The HM-901’s bigger sound edged out the DX90 as a match for the PM-1.

Our Verdict

I have to admit I am in love with my DX90. Perhaps the HM-901 is the more mature and natural-sounding DAP and the FiiO X5 has a better battery life but the DX90 has just the right type of tonality to make it a great match for my Merlin’s and pretty darn good on the rest of the gear.

The form factor and volume control also makes the DX90 a perfect travel companion combined with a suitable matched IEM. For those wishing to have a darker thicker smoother sound the X5 is probably going to be a more suitable candidate. These two companies are basically going head to head right now with Astell & Kern moving to a perceived higher ground and the HM-901 appealing more to headphone enthusiasts than IEM users for me personally.

Should you upgrade from the DX50? If you love the tonality of the DX50 then perhaps no need to upgrade since everything else is more or less the same. That includes the physical looks, functionality and the OS. But if you want a step up in resolution, a faster, cleaner engaging sound then the upgrade might make lot of sense.

Many thanks to iBasso for sending us a review sample of the DX90 and special thanks to Nathan Write of Ohm Image for the lead picture included in this article. Spiffing job and makes me feel like a rank amateur with a smartphone.

DX90 Technical Specifications

Line out
Frequency Response: 17Hz~20KHz +/-0.1dB
S/N: -119dB +/-1dB
THD+N: 0.0015%
Crosstalk: 115dB (1KHz)
Output Level: 1.7Vrms (1kHz 0dB)

Headphone out

  • Frequency Response: 17Hz~20KHz +/-0.1dB
  • THD+N: 0.0015% (32ohm load)
  • Output Level: 1.3Vrms(Low gain), 2.0Vrms(Mid gain), 2.8Vrms(High Gain)
  • S/N: -118dB +/-1dB(Low gain), -116dB +/-1dB(Mid gain), -115dB +/-1dB(High Gain) (32ohm Load)
  • Crosstalk: 75dB (1KHz,32ohm Load)
  • Output Impedance: <0.1ohm


  • Life: 8.5hours
  • Battery Charge Time: 3hours with AC adapter, 5.5hours with PC USB port
  • On Board Flash: 8GB
  • Audio Formats Supported: APE, FLAC, WAV, WMA, AAC, ALAC, AIFF, OGG, MP3
  • Case dimension: 2.52W x 3.98L x 0.67H (inch)
  • 64W x 100L x 17H (mm)
  • Weight: 140g or 4.94oz


  • USB cable
  • Coaxial cable
  • Burn-in Cable
  • Silicone case
  • Screen protector

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