interesting observations.  compared to the other DACs i had here, the Gung was tuneful and dynamic.  it wasn't the least bit soft or boring via USB.  it reminds me of the Naim gears i owned but with better tonal balance and timbre.

have you compared USB to the JKenny USB-SPDIF converter?  not that the JKenny is identical to my MF V-Link USB-SPDIF converter, but the V-Link made every DAC sound more subdued/relaxed and rounded.
 
maybe we should break this off into the Gungnir Loaner thread.

I'll get the Gungir measurements up tonight/very early tomorrow morning and will be trying out USB then. It measured a bit better with jitter than BNC with JKSPDIF, so I wouldn't be surprised if it sounds better.

Also keep in mind I'm speaking relatively here. Not saying the Gungir isn't those things. Also not saying I have great hearing. 

Haha, just trying to cover my ass for anyone that thinks otherwise!

I did some USB/BNC comparisons on the Gungnir. I'm pretty sure USB sounds better. The Gungnir overall sounded more "with it" and less soft. So, an improvement in all areas mentioned. Of course, I'd like to hear how USB compares to BNC from a better converter like the OR5. (The same applies to the Hex, which I believe is on the sensitive side in terms of the chain of gear behind it...it's probably limited by the JKSPDIF.)

The differences between the Hex and Gungir became more subtle after I switched to USB. Really, most of my thoughts from before still stand, just to a lesser degree. The Gungir still sounds a bit soft and slow in comparison, maybe slightly thicker sounding. But it does have a smooth, sweet quality to it. The Hex seems cleaner and more focused, but more condensed, as mentioned earlier. I like the more intimate nature of the Hex and think it helps flesh out vocals in any situation and helps with instrument separation/details in complex, fast, messy passages in genres like metal. The Gungnir might be better for, say, orchestral, as the more compact nature of the Hex lends itself better to 3-6 people bands with music that isn't particularly wide or spacious sounding (or whatever number...you get the idea). Just a guess, though, because I don't listen to much music that necessitates a wide, extremely layered soundstage.

In terms of dynamics, I found them comparable with the Hex being slightly more engaging. And in regards to the Hex sounding "cleaner," I thought it did a slightly better job pulling out details in the bass. It's hard to describe, but in some ways I found the DACs to be both more aggressive and more laid-back than the other in different ways. But if you consider the Hex has more of a roll-off in the very upper treble and that I find the Gungnir to be a bit softer sounding, it sort of makes sense. Keep in mind this was 16/44.1 tests without any software upsampling. I was actually surprised how not laid-back the Hex sounded compared to the Gungnir with this playback setup.

I touched on this in my other post, but vs. the Gungnir, I think the Hex does a better job conveying a sense of life, rhythm, and attack...I almost want to equate this to the underlying, emotional swings, movements, and beats that come from the culmination of the musical technicalities and the musician's unique "feel" for what they're playing and how they play it. Moments when there's a miniscule amount of blackness before everyone strikes heavily at the exact same moment, I felt the Hex handled that a bit better. Subtle differences in how a particular guitarists moves their hand and fingers across the fretboard or their picking techniques, the micro-nuances that bring out the underlying feeling and motion behind the chords, melodies, and overall music, I found the Hex did better.

Overall, I might consider the Hex to be more transparent. YMMV. This might also change if I ran the DACs in balanced mode. But, given the price of the Hex (especially of you want the USB input add-on or need to get a SPDIF converter), the Gungnir is a much saner purchase.

I'm becoming increasingly convinced that while NOS DACs do tend to have a particular sound to them and have known limitations (see discussions on NOS DACs floating around these forums), these limitations really don't play a huge factor during music playback. You'd think my ears would fall off based on how some rail against NOS DACs or that I'd hiss and howl every time I swapped from the Gungnir to the Hex, but I'd like to see how many could correctly identify NOS/OS DACs in blind testing (assuming good DACs overall). At worst, I think the NOS limitations impart qualities that could easily be found as pleasing to some, much like what you'd see with a well-designed tube amp that doesn't necessarily measure "excellent" in all areas. I'm guessing some or many of these limitations and poor measurements are below our hearing capabilities during music playback. Of course, certain hardware will probably handle a NOS output differently (in terms of ultrasonic stuff).

Wow, thanks for taking the time and effort. Pretty interesting results - upsampling to push noise into ultrasonic bands seems to have tangible sonic benefits. Definitely going to be keeping an eye out for this functionality as I continue DAC shopping.