[uncola]

neugrim you can hide the little dac behind your desk or something  definitely keep the asgard 2.  if you do want to get he modi, know the modi is in a smaller case that's steel not aluminum but it does look ok sitting on an asgard

 

[fallingreason]

The Icon HD does not have near the power capabilities of the Asgard 2. You can find the specs for each here:
https://www.nuforce.com/index.php?option=com_k2&view=item&layout=item&id=26&Itemid=189/#specifications
http://schiit.com/products/asgard-2 (click the specs link)

Get a Modi or ODAC to pair with the Asgard 2.

Its fun to look at numbers, but the HD/HDP headphone amp has gotten excellent marks by reputable reviewers.  HeaphoneAddict is a big fan of this unit as is 6moons.  (http://www.6moons.com/audioreviews/nuforce14/hdp.html)  They've driven everything I've ever had including the HD650 just fine.
 
I'm sure the Modi and Asgard 2 will be excellent, but that's $350, no?   I'd honestly rather spend $150 on the Icon HD and use that $200 saved on headphones or a cable for the headphones.. Just my $.02.   I couldn't be happier with my HDP and how simple the connectivity and how nicely it looks/fits on the desk.

 

[cel4145]

I couldn't be happier with my HDP and how simple the connectivity and how nicely it looks/fits on the desk.

Then why don't you sell your Centrance DAC mini and get you another one? (lol)

OP has the HE-400s and the AKG K712s. I own the HE-400s and the K612s (which are apparently as difficult to drive as the 712s) and an Asgard 2. It is a treat to have that power to drive those headphones on the occasion one wants to crank them up. Now that I have heard them with some power, I wouldn't give up the Asgard 2 for the much lower output of the Icon HDP.

 

[ProtegeManiac]

  Now that I have the Asgard 2 setup I'm reticent to return it and get the Icon HD - unless there is a big difference in quality.  Also, I like that the Asgard 2 can be used with or without USB.   Negatives to the Asgard's are the temperature - and I guess the fact I have to use it with a separate DAC.  Also the Asgard puts out a good amount of power - but I don't even know what spec to look at that to compare the two.  HOWEVER, I'm not enjoying looking at the little cheesy DAC on my desktop.  Lol, this is making me schizo.

 
DON'T. I seem to be the only one who reported this, but when I hung out for an hour or so at a local audio dealer's demo room trying out the HDP with a variety of configurations, it kinda sucked as an amp for m HD600. The bass was a bit loose, with too much bloom though the attack is soft, and the decay is a little bit much. A kick drum hit that sounds like a solid "THUD!" on, say, my Cantate, an Asgard, or Burson Soloist (the previous generation Bursons sound a bit warmer and softer for me) sounds more like a "boOOm-thwack," and bass guitar notes that should sound like "dum, dum, dum, druuummm" (last note is when the bassist slides his fingers down the neck) sounds like a "duwoooom, duwooom, duwooom, durrruuwooooom." I hooked it up as a preamp to a 300wpc amplifier on the floor driving some multi-driver Polk Audio RTi speakers, and while there is a bit more bass than the HD600 on any of those three other amps, it wasn't distorting - more like a really loud "THUD!" with a hint of a background "BOOOM" (which could be the speakers, and also the room, but anyway it doesn't get in the way), and the bass guitar is the same, just louder.
 
I'm not going to go into the details because anything supporting my guesses on why that is will inevitably end up in the territory of banned topics for discussion.

 

[fallingreason]

   
DON'T. I seem to be the only one who reported this, but when I hung out for an hour or so at a local audio dealer's demo room trying out the HDP with a variety of configurations, it kinda sucked as an amp for m HD600. The bass was a bit loose, with too much bloom though the attack is soft, and the decay is a little bit much. A kick drum hit that sounds like a solid "THUD!" on, say, my Cantate, an Asgard, or Burson Soloist (the previous generation Bursons sound a bit warmer and softer for me) sounds more like a "boOOm-thwack," and bass guitar notes that should sound like "dum, dum, dum, druuummm" (last note is when the bassist slides his fingers down the neck) sounds like a "duwoooom, duwooom, duwooom, durrruuwooooom." I hooked it up as a preamp to a 300wpc amplifier on the floor driving some multi-driver Polk Audio RTi speakers, and while there is a bit more bass than the HD600 on any of those three other amps, it wasn't distorting - more like a really loud "THUD!" with a hint of a background "BOOOM" (which could be the speakers, and also the room, but anyway it doesn't get in the way), and the bass guitar is the same, just louder.
 
I'm not going to go into the details because anything supporting my guesses on why that is will inevitably end up in the territory of banned topics for discussion.

 
I believe this, especially based on my DACmini pairing with my HD650's  better than the HDP did, though still not sure if it's the DAC or AMP difference...  If you believe the price difference is worth it I accept that.  
 
I will say that I do think that Schiit is a cooler company and it's great to support one that does their manufacturing in the USA.  =)

 

[juliusthecat]

I've used a pair of JBL LSR305s for about six months with a iFi Nano with these cables: http://www.monoprice.com/Product?c_id=115&cp_id=11509&cs_id=1150902&p_id=4778&seq=1&format=2 . 
 
I looked for a while for a balanced option, but this is a great combo, albeit above budget.  A bit awkward with RCAs on the front of the Nano, but highly recommend.
Don't use it for headphones at present.