Hello, I have not heard the DX90 but I have owned many Sabre-based DACs ranging from a few dollars to above a $1000.  The iFi Micro DSD stacks up very well against them.  Sure, it does have it's faults, but not anything that would make me say it has a "weak" DAC section.  I probably would not have commented since you say your comments are relative to the DX90.  However, when you put "weak DAC" in the title I would like to hear why such a strong negative title.  Even without comparison to the DX90 there is no hint of muddiness in comparison to any DAC I have owned.    
 
Usually "clean" refers to lack of distortion.  What distortion did you hear in the Micro?  What areas of the frequency response were troublesome and producing not so "clear" sound?  To my ears this DAC has very clarity, detail, and transparency.   
 
Did you use the iFi DSD as a pre-amp or direct into your Schiit amp?
 
I am curious about this DX90 since you have praised its DAC section. 

i used either the ifi's dac or the dx90's dac into the ifi's amp, out to my headphones- i listened only with my alpha primes.  as i said in my review, if i had no comparison, i would have said the ifi's dac was perfectly acceptable.  it was only in comparison with the dx90's dac that the ifi's sounded slightly blurred.  i know i'm not using a technical vocabulary here, but i don't know how else to describe it.  there was a slight lack of clarity in its sound, a blending of frequencies from different instruments making those instruments a little harder to define.  i wasn't focusing on the frequencies at which i perceived this slight blurring but my recollection is that it was in the mids and upper bass.  i was listening only to classical music.
 
the reason i put "weak dac" in the title is that i think its dac is the weakest link in an otherwise very impressive device.  it is the one element that i criticized; everything else was pure praise. in the review i make clear that the micro's dac is perfectly acceptable- it just wasn't as good as i'd hoped. when i bought it i was hoping that the micro's dac would be as good or better than the  dx90's.  then i would have just used the latter as transport, with a coax connection to the micro.  instead, when i'm in the right circumstances [i.e. wanting to use my transportable system and neither on the go nor at home to use my home system]  i'll be using its line out to the micro's amp, which i think is preferable the dx90's amp.

thought about your comment some more and decided "weak" was an overstatement, changed the headline.

Thanks for the clarification.  Everything you said makes sense.  I just wasn't sure of the degree of issues you were having with the clarity so interpreted it as more severe than it was.  Cheers.  

so... there are differences between DACs afterall?.. staying a lot in science forums almost convinced me that the DAC in 1$ players from ebay sounds the same as da vinci DAC...
 
would there be any reasonable reason for me to buy both idsd micro and hugo, or idsd micro should suffice?