@ClieOS OK, got it. No one is looking for a "sensational review" from a respected reviewer.  But you have to appreciate that as someone who reviews a lot of gear, you have heard/experienced more equipment than most folks on head-fi.  As such, we really *do* want to know how a product stacks up - i.e. would you spend your own money to buy one, given what else is out there?  My take on your review is the answer is 'No'; even though you state that the product is a great value, comparing features and price, etc.  That's all I meant by my original comment.

@ClieOS Thank you for taking the time to write the review, as well as your very thoughtful responses to questions.

@Krutsch Ok, the question of whether I'll buy the nano iDSD myself is related to a few more questions: First, do I have a need of a portable USB DAC like nano iDSD and second, are there better option for the price? The answer is 'no' and 'no'. I do not use my smartphone for music (given battery is already as short as it is on flagship smartphone) and rather carry a separated DAP for the job. Of course I also have a great desktop setup at the moment and nano iDSD won't be an upgrade. So are there better option  for a portable USB DAC+amp that is better than nano iDSD? Well, it depends what is better - If better means biggest soundstage or better clarity, then yes. If better means a tremendous headphone amp, then yes as well. But the thing is, is there any other single USB DAC+ amp unit that is better than all aspects found on nano iDSD? I don't think I know any. One of the biggest feature on the nano iDSD is its native DSD / DXD decoding, and that is pretty much unique to iFi and you won't find another portable USB DAC+amp that has the same capability of nano iDSD - but as I have also said in my review, I don't actually care that much about DSD / DXD since I don't use them. So you have to realize that I don't really have a lot of reason to pick a nano iDSD up, and as such, it is reflected on my review. But for anyone who do want DSD / DXD decoding on an OTG devices, I have no problem recommending nano iDSD, given it is probably the only of such device in the market right now that is under $200. In fact, you can double the budget to $400 and won't find that many USB DAC+amp that do all the native DSD / DXD decoding on-the-go. That's what I means when I said in the review that nano iDSD 'stand out from the sea of portable amps and DAC in the market'. That is, it has a unique set of features that will appeal to those who need them, but might not be the same for others. If I were to go out on my way to tell everyone to pick one up, then it will be just hyping for no good reason.

p/s: The reply above is meant to go above Krutsch's reply, as the only way to edit is to delete the original reply and repost again, hence why his reply came out before mine.

ClieOS wrote: "No competition, micro iDSD just smashes both nano to pieces. I'll write a review on it later".
 
 While the Nano probab. sounds competitively decent, IMHO, you should've waited and presented both reviews concurrently (or done a quicker review job with the Micro, to get them both out the door simultaneously). Some folks whose needs are immediate may, later, feel "forced" to upgrade ... that's human nature ... and product marketers may time/schedule street dates to take advantage of this. 
That said, it is understandable that Reviewers are a bit under-the-gun, too ... sample may have to be returned to manuf. ... or if the review sample is free, and the reviewer leans a bit politically favorable. 

I don't want to do quick review, or at least try to avoid doing it as much as I can. I am firm believer that a full review should be written by the person who actually took the time to understand and use the product on a regular basis, not just a quick half an hour playing around then mashing everything together. The accumulation of experience and the reflection of thought can't be short-cut, at least not for me. I don't actually enjoy spending hours writing stuff - so unless it is worth my time to sum up the thought, I really won't want to write it. That's my own respect to the work.
 
Back in the old days when I first joined head-fi, it took people months and sometime year to feel comfortable to write a full, really in-depth review. We are already in too fast a world, and it is not always a good thing.

@ClieOS - Thanks for your comments. Much appreciated!

@ ashutoshp - Thanks ... interesting article.

@ClieOS - You mentioned, "I also have a great desktop setup at the moment and nano iDSD won't be an upgrade." I am interested in a "great desktop DAC" which is known for a big soundstage. Any suggestions as to put on a short list in the under $1000 range?

My current setup is iDAC + iTube, but I also have Asus Essence STU and STX II, Audiotrak Dr.DAC3 and FireStone CustomCute - all excellent DAC of their own. Of course, I also have the micro iDSD with me. For the $1K budget, I'll go fir the micro iDSD + iTube, which combines an excellent DAC, headphone amp as well as tube buffer for desktop speaker. That's almost a complete setup for any occasion.

Nice review. This one adds to others I have read and partly one of the reasons I ordered the iFi iCan Nano. I really like that little amp. Makes for a nice combo with my iBasso DX90.
 
I'm thinking about getting the iDSD Nano and pair the two for my laptop and use for portable sound-system.

Thanks so much for your comments gentlemen. 

Not true. The GeekOut 450 does DSD 128 natively as well as 32bit PCM. It has a better amp as well. I'm honestly trying to compare the two right now though. 

@SoAmusing777 Digital volume control by itself means the DSD decoding in Geek Out (or in fact in all ESS chips, even the TOTL ES9018) is not actually 'native' by the meaning of the word. True native DSD decoding can NOT have any digital volume control. To have digital volume control in DSD playback, it means the DSD data stream must be internally converted (on the chip's level) to PCM first, then followed by the volume control and D-to-A stage. For what I know, ESS is among one of the DAC solution being considered by iFi during iDSD's R&D, but ultimately rejected because one of the design goal of iDSD range is to have true native DSD playback, up to the chip level.

@ClieOS  did you ever compared the ifi to the schiit modi? If so can you comment a little bit on that?

@the Ortherion Can't help you there as I have not listened to the Modi myself.

The maximum output of the modi is 1,5V vs the 1,6V of the ifi. Do you think that will make a huge difference? 

@the Ortherion No, voltage itself doesn't tell the whole story. If you were only looking at spec, I'll think nano might have a small upper hand. But until actual listening, I don't think spec alone can tell me which is better.

Hello @ClieOS, first thanks for you review!
Can you compare the Fiio E10K with the nano IDSD (i am interested in the DAC in both of them, i dont mind the amp in the nano ).
Many thanks!

@Thazzz While E10K is an excellent USB DAC/amp for its price, there is just no comparison to iDSD nano purely on their DAC performance. If you are taking using one of them purely as source to feed another amp or loadspeaker, then I have no problem recommending iDSD nano over E10K.