you should be able to get a gamma2 easily new.  just contact Mister-X on the AMB website.  very reasonable price the last i heard.

Hmm, too bad you couldn't hook up HD800s with the dynahi and sabre. I could have included my balanced cable if I'd have known. That combo should be really special.

Oh, sorry. I thought you had 800s. IMO, the X-Sabre and HD800 are a perfect match, as if built for each other.

Well, I've been sitting on my notes for about a month now, and I should stop putting this off. 

I picked up a used Audio-GD NFB-3.2 locally for $150. Quite the deal, in my mind, for how it sounds. It's not a technical masterpiece, but it has some really nice traits that makes it something I dig quite a bit. For now, I think I'm just going to stick with my NOS-1704 as my main DAC. I also no longer have the PWD MK1 on hand.

PWD MK1 vs. NFB-3.2

Both of these DACs have selectable filters, though the NFB-3.2 has more diversity in that regard. I set them as close as possible, with the NFB-3.2 at 8x OS, minimum-phase and the PWD MK1 on one of its MP filters. I believe it was filter 3, but it appears I forgot to make note of that. This was with 16/44.1 material.

The PWD MK1 had a noticeably cleaner, more spacious sound than the NFB-3.2. In terms of layering, it just was not even a fair fight for the PWD. The NFB-3.2 had a tendency to sound looser and less well-defined compared to the PWD. However, the NFB-3.2 also had a more rich and powerful sound than the PWD. For example, where the bass drum might have a more present and clean kick to it on the PWD, the NFB-3.2 gave it a bit more power and life at the expense of sounding less focused. Occasionally, I thought the NFB-3.2 had better echo and decay properties, even though the PWD always sounded more spacious.

The NFB-3.2 seemed to have a slightly more black background and darker tonality than the PWD. The PWD was more detailed and resolving sounding, and in general it sounded less laid-back. In regards to this and the details in the last paragraph, the NFB-3.2 would start to become more and more congested sounding and less controlled with complex material. Where as the NFB-3.2 was generally more euphonic and lively for me, the PWD sounded better composed, if maybe a touch on the lean side.

On some of my harsher tracks, the PWD sounded noticeably more hashy than the NFB-3.2 Indeed, the NFB-3.2 was almost always the smoother sounding DAC of the two, and I tended to prefer its tonality and timbre.

Don't get me wrong...all of the Wolfson-based DACs I've tried recently carry this certain agreeable quality to them relative to some of the other delta-sigma chips/DACs I've sampled. The PWD was not my favorite among the three, including Gamma2 and NFB-3.2, but it had some characteristics that it really excelled at.

Now, given the choice, I run 2x or 4x OS filters on the NFB-3.2. I generally use the 2x, minimum phase, soft-knee filter, and I wanted to compare that setting against the PWD as well. As I guessed, the differences were more striking. The NFB-3.2 was a good deal more laid-back sounding than the PWD, but it didn't lose much in the way of resolving power or liveliness. I thought this filter setting on the NFB-3.2 gave it a better sense of presence and rhythm, and the PWD did sound flatter in terms of liveliness, swing, and dynamics in comparison. I summed it up in my notes by saying the NFB-3.2 was more about presence and the PWD was more about precision, whatever that means.

NFB-3.2 vs NOS-1704

For this comparison, I set the NFB-3.2 to filter 1 (2x, MP, soft-knee). This most closely matched the NOS-1704's performance. This test was particularly interesting to me, given A) I really like the sound of these two DACs, especially if the NFB-3.2 is on F1, and B) the NFB-3.2 on F1 is probably the closest I've seen and heard a delta-sigma DAC match the traits of an R2R NOS DAC.

The first thing I noticed was the bass presentation. The NOS-1704 produced bass pitch and texture the NFB-3.2 simply could not match. Then again, I d o believe I've most preferred how this DAC handles bass. On a particular track, the bass guitar had an amazing sense of growl to it on the NOS1704. The NOS1704 was overall a smoother sounding DAC. It was a touch less detailed and resolving, though still much closer to any of the delta-sigma DACs than the Metrums.

On the other hand, the NOS-1704 had a mushier, more intimate, less clear quality to it than the NFB-3.2. The NFB-3.2 was more spacious sounding and had better separation between everything. Yet, despite sounding a bit more 3-dimensional, the NFB-3.2 still did not do as well with layering. The NOS-1704 has more tangible, more realistic sounding vocals. The NFB-3.2 had a blacker background and was perhaps a touch more dynamic, except for how it handled bass.

With all of the filter options, I thought the NFB-3.2 was a very well-balanced DAC, though on the smoother side. I'm very curious to hear the newer, Wolfson-based Audio-GD DACs.

I've decided to use the NOS-1704 as my primary DAC for now. It best captures the "feeling" and "emotion" of music for me, though the Hex was also excellent (had to sell it for moving money). It is on the smoother side, but unlike the Metrums, it is better with details and has better distortion performance. Jumping back to delta-sigma DACs tends to give me a slightly more sterile, slightly leaner and flatter quality that, in the end, outweighs the other desirable traits that seem inherent to them. I'm not sure what I would think of an oversampled R2R design and where that would fit into this mix, though I'd love to experiment with an R2R DAC with selectable filters, if one exists.

I am more than happy to listen to any DAC, especially custom ones! Well, I say that now. I'd send more of my own DACs out on loaner tours for all if shipping didn't add up so quickly.