Equipment Used: Soundaware D100 digital transport BNC out -> Metrum Acoustics Amethyst Coax SPDIF in -> Mixture of Creative SB1240 and Focusrite 2i2 (first gen) -> Surface Pro USB Note on new, experimental methodology: I wanted to experiment with a new measurement technique, so to speak. I noticed the SB1240 and 2i2 excel in different areas relative to each other, which is to be expected. One will have noise in a lower spot than the other, and vice versa. They have their own inherent harmonic distortion characteristics. So on and so on. Sometimes measurement results wouldn't be totally representative of the DAC alone, but rather have a few ADC characteristics thrown in. That's the downside of cheap (but surprisingly good for what they are!) ADCs. So, for many of these tests, I did some Excel work and more or less combined the results in such a way to minimize the individual characteristics of the ADC. However, in the case of the jitter tests, the results were very similar between the two ADCs, but just dissimilar enough that combining them basically cancelled everything out and made the results look clearly unrealistically good. In that case, I defaulted to the SB1240 rather than try to combine them. Everything else, though, I think is fairly indicative of the Amethyst's performance. (Sine wave output in ARTA handled by SB1240.) 1KHz, -1dB, 16/48 - My rough calculations put THD at around 0.0077% up through 20KHz. This is similar to the Menuet. I briefly squeezed in a quick look at the Pavane during a mini-meet and saw it closer to or slightly below 0.005%. Believe it or not, I never properly measured the Adagio! Here's a look at the same results as above, but focused on 0Hz-1KHz. Very clean. This was about as low as my ADCs would go. (The SB1240 doesn't have the lowest low-end noise floor, and the 2i2 had a higher noise floor since I had to raise the gain due to single ended output on the Amethyst. With a balanced DAC into 2i2, I can get a lower noise floor.) 1KHz, -3dB, 16/48 - From here on out, I thought it might be interesting to see how the Amethyst handled this test as I started dropping the level of the 1KHz sine. Very minor changes. THD roughly calculated at 0.0081%. 1KHz, -10dB, 16/48 - THD roughly calculated at 0.013%. 1KHz, -60dB, 16/48 - Less interesting than the sine output below. 1KHz, -90.31dB, 16/48 - Refer to sine output below. Here's a look at the -60dB sine wave. You can some minor "wiggling" at the top and bottom of the waves. I have not checked this on many other DACs before to see if this is a consistent behavior, but I was mostly curious to see if this repeated itself with a 24-bit signal. The Bifrost Multibit actually had a similar and slightly more noticeable behavior on its -60dB sine wave, but I never published those results. I don't know enough about this, but perhaps it's quantization stuff like with the -90dB test? The 16-bit, -90.31dB, 1KHz signal shows the 3-step pattern we would hope to see in this case. This is a good looking result given the limitations of my ADC.