I bought the two piece DAC & amp and set them up on my desk at home. I also set my old Little Dot 1+ up there for the photo op.
It is very easy to A/B test this because the computer quickly switches back and forth between the DAC and the sound card when I plug or unplug the USB cable, and there is a source switch on the amp.
A) Computer sound card to Audio-gd amp
B) Audio-gd DAC + Audio-gd amp
A) Sounds great. Not remarkably different from the Little Dot, but my Grados are easy to drive. The Audio-gd amp doesn't pick up the noise floor from the computer power supply like the LD did. There is a very slight noise floor from the amp when it's turned up high with no music, but playing music at that level it would be irrelevant.
B) With the external DAC there was a slight improvement in clarity. It seemed like more information was able to get through, especially in the highs. Going back to the old setup sounded a little flat. The music with the DAC also sounded more analytic. The improved treble extension made the bass sound less pronounced by comparison. I went back and forth to see if bass was lacking in this setup vs. just the LD 1+, but it was there all along; the higher definition in the treble gives the impression that the bass is softer. However, all these differences were subtle.
Then I went into my Control Panel settings and changed the external DAC from the default 16 bit/48 khz to the max setting of 24 bit/192 khz.
Wow! Okay, now the resolution is noticeably improved, particularly in the top end. There's no roll-off of detail in the treble, it just articulates precise detail straight through to the top. All my music sounds different. I listen to a lot of jazz, and it just gained a new dimension. I went through and listened to a couple of my favorite albums to see what they sounded like. The brass instruments and drums come through in shattering detail, However, this improved clarity also exacerbates the impression of stronger treble. Now I'm not a bass head by any means. I love midrange, and I don't have any heavy bump tracks in my demo rotation. But the clarity from the new DAC (or rather, the 24 bit/192khz setting) changed the perceived shape of the music. Reminds me of when I demoed high-end Grado headphones in a store and went with the SR125s because the GS1000's were too bright. The same thing is happening with my DAC. It sounds better, but it seems to have thrown things a little off balance from what I'm used to.
So I got curious about my sound card settings, went into my Control Panel again, and changed the setting for the sound card to 24 bit/192 khz.
Wait a minute, what? My Dell laptop has a built-in DAC that can do incredible resolution, and it came with a lower resolution setting? Why would they do that? Anyway, now the A/B comparison is totally changed. With a control panel setting, I made my computer sound card sound almost as good as my Audio-gd DAC-19... Almost. The Audio-gd DAC still sounds slightly more transparent, but it's a close call. It's kind of surprising, because the Audio-dg DAC is huge.
In conclusion, the Audio-gd equipment clearly improved clarity and resolution over the LD 1+ setup, and killed the noise floor. However, my built-in sound card apparently can do the same thing, which means I'm not getting much extra from the DAC-19 except heat and a barely audible improvement in transparency that's borderline imagined. And in both cases, the higher resolution seems to have cost something in warmth. It makes me want to start shopping for headphones with a stronger bass curve. I'm open to new headphones anyway, because I need some closed cans for the office. I'll give it some more listening hours and give my brain a chance to adjust, then evaluate my next move.
Edited by earthtodan - 7/13/13 at 4:00pm