Hi!! No, finally I didn't buy the Asgard 3.
Now I use only a Chord Mojo much much better than the NX4, it's be in other league.
And I returned the Sundara because it's cause me fatigue. I prefer the hd660S less detail but more comfortable and sweet for long sessions.
Have you the Sundaras?
Yes, I have the Sundara's. Funny you mention the 660s. I returned those because I preferred the the detail and Soundstage of the Sundara's. I found that if there was any fatigue with any of my headphones that I use an eq to tame that. Amplification and dacs is where I spent most of my research. I ended up with a Monoprice liquid Spark for $85 fed from the mb of my pc. Returned E30, L,30, A90, THX 788, SMSL m200. None of those provided any noticeable sound differences to me. The liquid spark provided the most power for SE use of the bunch. I have no desire to ever utilize balanced as I found no difference with that as well, other than more power.
I found that if you have a dac that does not inject any noise/distortion from a pc (mb in my case) and a decent $100 amp you are Done with that part. Then you just experiment with headphones. For me I love the sound and feel of the Sundara's. I also picked up a set of Sivga Phoenix that provide a nice contrast to the Sundara's, and they need no amplification whatsoever. Finally, if you are truly on a tight budget all you need for cheap headphone Nirvana is a set of Koss kph 30i's. Picked them up for 19 bucks during bf and they are stellar for that price, plus there is no need for external amplification, though they do benefit from that. In fact they are my most comfortable set when modding them with the foam earpads from my Grado sr325 i's (not the originalals but the more comfortable replacements).
Edit... forgot to mention the use of an eq will make all the difference in the world. I know that some do not like to use it but for me it is a valuable tool.