Blind test: 6 DACs compared - Page 10  

Hi Skamp,

Here you see the harmonic structure of the overtones that are generated during reproduction. Note that those overtones are well below the quantization of a 16 bit recording.

You are talking about two things here, harmonics that are associated with fundamentals of musical tones are a different kettle of fish from harmonic distortion. as you know if you play a note such as a note on a trumpet you'll get loads of harmonic energy (some actually above the fundamental) well within the audible spectrum descending in energy eventually as the frequency of the harmonic increases. You want to capture the audible harmonics and you'll get it down to about -96db with a bog-standard 16 bit ADC. Most of the very high harmonics though will be utterly inaudible as they both occupy an area of low sensitivity (the ear is most sensitive between 2K and 5K above 5K sensitivity declines markedly) and are at very low levels as well and masking takes care of harmonics that are close to other frequencies but substantially lower in energy. 

Whenever an instrument, a voice or a DAC (as in your case) is recorded, the harmonic content falls below the quantisation (not to any level of significance - see above) , that means it is NOT on the recording. Therefore your recordings do not show much the audio quality of the DACs.(harmonics 50db on the fundamental or so down are afaik inaudible so irrelevant let alone harmonics 100db down - when you apply a filter at 20K all you are removing are harmonics (unless you are using synthesizers) and even instruments that have harmonics extending to 100Khz are not audibly affected by filtering off these high harmonics. There were experiments way back in the 70s (JVC researchers did this) that confirmed this and aside from the very dodgy Oohashi paper nobody seriously (excepting James Boyk) claims that these harmonics are in any way an issue   At least they don't show everything there is. 

You make that anti-jitter thingy don't you ?

Out of interest have you done any controlled blind listening tests on the effect of your anti-jitter thingy. I ask as jitter in most competent is already at extremely low levels and to date there has been no serious evidence to suggest that jitter in pretty much any half-decent (excluding the McIntosh music server and Zanden DAC) digital component reaches audibility. Of course anecdotes abound  but good empirical evidence for jitter audibility in day to day experience seems absent...I've been researching this for many years and neither manufacturers nor serious audio bodies such as AES, BBC, NHK and so on have found jitter to be any kind of problem but perhaps you have done some testing, if so it would be really interesting to hear about it !

Room acoustics always change with speakers in them. It's measurable.

so when does the answer key show up? they sure sounded pretty much the same to me except for D which sounds a bit more lifelike/pleasant

so when does the answer key show up? they sure sounded pretty much the same to me except for D which sounds a bit more lifelike/pleasant