Accessories Review of iFi Audio Micro iDSD USB OTG DAC/amp with lots of pics!!!

Using micro iDSD as a charger.



Under the hood.

Moving on to the internal design, I discovered that Micro was actually Crowd-Designed when iFi made their original post in March of 2014 on Head-fi, asking for members of this #1 audio community to list what they would like to see in this upcoming flagship DAC/amp. We are used to hearing Crowd-Funded term when companies seek money to turn their ideas into a real product. Here, we are talking about iFi Audio which is a subsidiary of Abbingdon Music Research (AMR) - one of the UK's largest manufacturers of high-end audio systems that cost up to $100k, a successful company that has been in businesses since 2000. Despite all this credibility, they opened the forum discussion to build a list of desired features by asking the Crowd who this Design was intended for. In today's audio market this is very rare, especially among reputable established companies.

Unfortunately I didn't follow their original Crowd-Design thread until now, but it's a truly fascinating read I highly recommend to check out here: http://www.head-fi.org/t/711217/ids...d-the-new-firmware-flavours-are-here-page-138. In addition to following everything from "birth" of the ideas, it contains a very well organized index page with links to corresponding posts going over every single design detail. Furthermore, iFi is very active in Head-fi community, and I see constant interaction and replies where this thread continuous to grow with more info.

Block diagram of the design:



I'm not going to rehash all the details, and I already covered all the ports and controls in a Design section of my review. One thing to keep in mind, with a selection of Burr Brown dual-core DAC chipset which actually utilizes 2x DAC chips across 4 output channels, you have a Native DSD/PCM support of every available high resolution format. We are talking about up to Octa-DSD speed of DSD512, obviously supporting Quad/Dual/Single DSD256, DSD128, and DSD64, and also double/single speed DXD with 768/705.6kHz and 384/352.8kHz, and PCM from 44.1kHz to 768kHz. I wasn't even able to find DSD512 samples for listening, and thanks to iFi samples included with iPurifier2 on usb stick, was able to play and to verify DSD64/128/256 using Foobar2k playing on my aging laptop. Of course, this is a universal audio interface and every other lossy and lossless audio format will be supported.

Sound analysis.

A lot of people just assume because Burr Brown DAC is in the picture, it’s a slam dunk when it comes to sound quality. Any DAP or DAC/amp architecture has many variables which all contribute to a final shaping of the sound. I have a few DAPs using PCM1792, yet they all sound different. This was my first experience with an audio gadget utilizing DSD1793, and I’m sure it will sound different from others due to iFi unique tuning of the amp section. Luckily, due to plethora of inputs and output, you can also separate DAC and amp for a better evaluation. But combined together, Micro offers a very addictive smooth analog detailed expanded neutral sound that brings up the best in any type of headphones regardless of their sound signature.

I can imagine that some people will expect a sound analysis based on evaluation of various parts of the frequency spectrum, but in reality we hear the sound not from a pure DAC/amp perspective, but rather colored by headphone signature. I will cover various headphone pair ups with relatively comparison to other DACs/amp in Pair-up section of my review, but in this section I want to bring up a few other interesting observation about Micro iDSD sound performance.

With popularity of the original Nano iDSD, I’m sure many would be interested to know how Micro compares to Nano. Fortunately, I was able to get my hands on Nano as well for review/comparison. To my ears Micro sounds more transparent, more multi-dimensional (even without 3D holographic effect), more dynamic, and with blacker background. Of course this should be expected considering a more advanced design and a different selection of components. But in this case it wasn’t “just a little bit better” but actually noticeably better. At the same time, for a portable convenience at less than half of the price, Nano definitely deserves a serious consideration.







Going back to Micro, you have an option to either use it as DAC/amp or Amp by itself. I found this next test to be very interesting because Micro combination of DAC/amp sounds fantastic, but while testing amp by itself I found the sound to be not as dynamic or layered and lacking some transparency. Don't get me wrong, amp is actually clean and relatively neutral, but the sound was missing the smooth detailed dynamic magic of Burr-Brown chipset. To take full advantage of that, you need to either use digital/USB input or Coax input.

With Coax input you bypass your source's internal DAC/amp and go straight into Micro where you can either use an electrical RCA Coax cable or optical Toslink cable, depending on your source. If your source supports both, like in some DAPs where Coax and Optical (mini toslink) inputs are combined, after a close a/b comparison I consistently hear with optical connection the sound being a little smoother and slightly more refined. I went back'n'forth many times to rule out a placebo effect, and every single time I found that I prefer optical interconnect over coax cable. If your source doesn't have optical output, Coax cable is still a great alternative, but otherwise - go for optical connection.







If you want to use your smartphone as a source, now you have access to a direct USB OTG digital connection. Testing with my Galaxy Note 4, I found no EMI interference, excellent pair up with all of my headphones, dynamic analog smooth detailed sound, and overall no major difference in sound quality compared to Micro pair up with other DAPs through coax/optical, though maybe just a little bit smoother and warmer with Note 4 in comparison to dedicated DAPs.





One advantage of using Micro digital input is that it has a built-in iPurifier Lite. You can't really disable it to note the difference, but I was able to use iFi standalone iPurifier 2 to hear the advantage of its functionality in series with USB port. I ran the test using my Note 4 as a source/transport, and found that Micro (w/built in iPur Lite) vs Micro (w/iPur2 in series) yielded another noticeable change where the background became blacker, leading to a cleaner on/off sound of the notes with a faster transient, especially in instrumental tracks.

The same test using my Note 4 as a source and Nano vs Nano (w/iPur2 in series) yielded a very noticeable change with background becoming blacker and a significant reduction in background noise. It actually improved Nano sound quality making it more dynamic, more transparent; maybe not on a level of Micro performance but definitely with an improvement. The only problem - it adds a bulk to Nano iDSD, making it less portable.





Of course I can't finish sound analysis section without talking about XBass and 3D effects. Activating XBass resulted in what I hear as a narrow and well controlled sub-bass boost that doesn't spill into lower mids and has a very subtle effect on mid-bass. I definitely hear it as a well controlled boost, focusing mostly on sub-bass without affecting too much mid-bass or muddying the mids.

While testing, 3D holographic toggle had a bit of a polarizing effect on me. Enabling 3D seems to affect only upper mids/treble region, acting like an exciter effect, adding some airiness to the sound, and creating a wider/deeper perception of the stage. To my surprise I found this effect to work not as good with every pair of headphones. It works great with warm and neutral signature headphones, but when used with bright headphones - it can make treble harsh and grainy. Example, PM-3 and A2000Z benefited from Micro 3D effect, but ES60, EL-8C and DN2kJ – not as much.



Pair-up and Comparison.

I think this “pair-up” section is the most important in describing the sound of Micro because it gives you a better perspective with a relative comparison of how other headphones sound with Micro and how it compares to a selection of other DACs/amps. In this test I used Micro connected to my laptop, and selected ES60, PM-3, EL-8C, and U12 for listening comparison with Micro iDSD, Nano iDSD, Schiit FULLA, Cozoy Aegis, and GeekOut GO450. Below are my listening notes with each pair of headphones.

Westone ES60 CIEM.

- w/Micro - hissing is under control with a gain switch (of IEMatch), smooth detailed sound, punchy extended tight bass, smooth detailed mids, well defined extended treble, smooth analog detailed tonality, and excellent transparency and layering/separation of instruments.
- w/Nano – more background hiss (can’t take advantage of gain switch), the sound is not as smooth as Micro, still a punchy extended bass, but not as articulate in comparison to Micro, mids are revealing and detailed, but not as smooth as Micro, treble is very similar and so does soundstage expansion.
- w/FULLA - a lot of hiss and distracting EMI crackle, soundstage is a little wider in comparison to Micro, the sound is bright and detailed, bass is not as tight and sub-bass is extended but not as deep as with Micro, but still, the bass is fast and punchy, mids are brighter in comparison, a little more upfront though not as smooth, also treble is brighter and with more crunch.
- w/AEGIS - a lot of hiss, have to use a minimum volume setting (too much default gain, not good with sensitive multi-BA monitors), and I hear a lot of background noise. The sound is balanced, detailed, bright, with a punchy extended tight bass, detailed revealing mids, and a well defined extended treble.
- w/GO450 - using 47 ohm output I hear less hissing/noise - but sound is dull and not as detailed, when switching to 0.47 ohm out – serious hissing, but sound is more detailed. With the later one, I hear a balanced detailed revealing sound, punchy extended tight bass, detailed revealing mids, and a well defined extended treble.

Oppo PM-3 planar magnetic full size.

- w/Micro – I hear a smooth detailed sound, punchy bass (but not as fast), smooth clear mids, nice smooth clear treble which is not as airy or extended. In this pair up mids sound very natural, probably the best PM-3 pair up I heard to date. I was a bit surprised since PM-3 is warm smooth to begin with, but Micro made them shine, especially with 3D switch on.
- w/Nano – it was a bit short on power to drive PM-3 to their full potential, definitely a bit of a stretch for Nano, the sound was not as smooth, less revealing, not as transparent or layered, it was clear but not as detailed, and mids were a little less natural.
- w/FULLA - nice deep punchy bass, tight and articulate, but mids didn’t sound as natural, and the sound was not as transparent or layered, a bit flat, though treble was clear and well defined – the star of his pair up.
- w/AEGIS - nice deep articulate bass, but mids sound a bit off being a bit bright and unnatural, nice extended treble with a good airiness.
- w/GO450 - great bass impact, bright detailed mids, nicely extended treble, and a decent transparency.

Audeze EL-8C planar magnetic full size.

- w/Micro - bright revealing fast sound, has a slight metallic sheen, punchy fast bass, bright analytical mids, airy extended treble. Mids are not as organic or natural. I was a bit surprised, but didn’t like this pair up.
- w/Nano - bright revealing sound, very noticeable metallic sheen, punchy fast bass but not as much sub-bass, bright analytical mids though could be a bit harsh with some songs, crisp extended airy treble. Mids could be a lot more smoother.
- w/FULLA - bright revealing fast sound, fast punchy bass, bright analytical mids, airy extended treble, still traces of metallic sheen, and sounds is not as natural.
- w/AEGIS - bright revealing sound, metallic sheen, too vivid, fast punchy bass with a noticeable sub-bass extension, mids are bright revealing but slightly harsh, treble is bright crisp airy.
- w/GO450 - bright revealing sound, articulate fast tight bass, mids are a bit shouty, bright, revealing, not as metallic as with other pair ups. Treble is crisp and extended. This pair up yields a touch less of metallic sheen.

64 Audio ADEL U12 IEM.

- w/Micro - zero hiss (in Eco gain), smooth detailed sound, fast deep articulate low end with a nice punch, smooth detailed mids, smooth clean well defined treble. Nicely expanded soundstage, even works with 3D switch.
- w/Nano - a little bit of hiss, smooth detailed sound, deep articulate low end with a fast punch and a nice sub-bass extension, but bass is not as tight as with Micro. Mids are smooth and detailed, but not as detailed as Micro, and I also hear a clean treble though not as extended. Micro feels like it has a little better retrieval of details with U12.
- w/FULLA - a little hiss, sound is a bit congested with overpowering low end, and not as transparent or detailed. But overall tonality is warm and you can hear a tight low end punch.
- w/AEGIS - too much power for these IEMs, too much noise/hiss, can't even play it from laptop, this DAC/amp is not good for majority of sensitive IEMs.
- w/GO450 - (0.47 ohm output), smooth warm sound, low end is not as tight but still has a good sub-bass extension, warm smooth clear mids but not as detailed, clear treble with some roll off.

With some other headphones:

- Micro w/T5p.2 - bright revealing detailed sound, not as much body or sub-bass, fast mid-bass punch, lean lower mids, bright analytical upper mids, a bit harsh with some traces of sibilance, bright crisp, airy treble.
- Micro w/R70x - excellent pair up with a very natural detailed sound, articulate punchy mid-bass, lean detailed mids with organic sound quality and excellent retrieval of details, extended crisp treble, excellent soundstage.
- Micro w/MSR7 - great pair up with a clear detailed sound, not too bright, punchy extended bass, nicely balanced mids (not too full or too lean), mids are definitely not as bright as with some other sources, and crisp detailed treble. Has a great soundstage expansion as well. Overall sound is well balanced and detailed.
- Micro w/DN2kJ - good pair up, upper frequencies are under control, but still a bit bright and with a more mid-forward signature. Bass quality is good, but not as much quantity, sound sig is more J shaped.

Conclusion.

When it comes to my casual headphone listening at home, I found that any USB DAC will do because they all improve the sound of my aging ThinkPad T430s laptop. But it was never as enjoyable until I switched to Micro iDSD and now can't even think about using anything else. Micro's smooth analog detailed sound characteristics just works with any pair of headphones regardless of their sound signature. Micro's design has an amazing flexibility to accommodate any audio setup, portable or desktop. And due to its ability to play everything up to and including Octa-speed DSD512, instead of enjoying my usual selection of EDM tracks, now I'm searching on-line to find exotic DSD128, DSD256, and DSD512 classical orchestra performances. Did I become a fan of Mozart and Chopin music renditions? Not really, but I'm fascinated with being able to play 1.5GB DSD256 audio files from my laptop without skipping a beat or a string.

I'm already anticipating questions after the review asking me how does Micro iDSD compares to Chord products, such as Mojo or Hugo. I can't answer that because I never tested any Chord products. That would certainly make an interesting comparison, especially since Mojo is in a same price category. But until then, Micro iDSD will have a solid place at the top of my USB DAC/amp food chain because no other product I've tested in this category comes close to its performance and sound quality. My only wish is for iFi design team to be able to pack performance and sound quality of Micro iDSD into Nano iDSD footprint, turning this transportable into fully portable.