Sean, thanks for the thoughful response. First thing I would like to know from you is, are you set up to try and replicate this test at some point? If you have the needed ancillary gear, and your DAC has an upsampling defeat switch, I'd love to see what you would come up with here.
61, let me address your proposal first: the problem with this is that to listen to such a CD-R, you need to put the signal back through one of the DACs again, or another DAC - you cannot listen to an 'unconverted' signal. So your test would have the effect of comparing a signal that's been digitized and converted twice against one that's been so processed once, which I'm afraid wouldn't be very useful. Remember, in the set-up I describe above, you are not hearing the two DACs [or two DAC modes] pitted against each other, but rather separately compared one at a time directly against the analog feed they are processing the digitized version of. Also, the random component you mention couldn't make your test 'blind', because you would have no way of comparitively evaluating what you were listening to unless you noted the track numbers as they came up, in which case the test is no longer blind (it is generally not possible, for the same underlying reason, to construct a 'blind' test run all by yourself - someone has to be able to take note of which choice the listener is evaluating at any given point in the test, even if that person doesn't know which variable that selection actually represents, in the case of a 'double-blind' test, which requires yet a third person).
Now, if in my set-up proposed above, I had had two identical digital outputs on my ADC, then a friend could have helped me to do a blind ABX test using both DACs and the direct analog feed at the same time, since my preamp does have two tape monitor inputs. As it is, my CD-R recorder has one S/PDIF output on RCA and one Toslink optical, which would have confounded such a test. My Theta does happen to have its own digital record loop on RCA, so I could send a feed to the MSB, but that would introduce an extra digital cable running to the Link. While running the test as a blind ABX would be interesting and valid to do, if you are able to try the procedure I detail above in your own system, I think you will wind up agreeing with me that it is very useful and illuminating in and of itself.
Getting back to your points, Sean, I can't argue with your caveats, and indeed do believe that I essentially acknowledge the main thrust of your comments in my posts: that this test can only evaluate the particular components under review, and should not be construed as an overall indictment of the upsampling technique. It was a provocative result, however, precisely because the other factors affecting the sound that you bring up (parts quality, filtering scheme, power supply, etc.) stayed the same when I compared the different modes (no upsampling, 96KHz upsampling, 132KHz upsampling) present within the Gold Link itself. But as you correctly say, implementation is everything. The observed finding that the Link's output most closely resembled its input when upsampling was defeated is what prompts me to urge others, some with other kinds of upsampling machines, to try and run this test themselves if they can.
Obviously, the only final conclusion that can be drawn from my own experience is that I prefer my reference, but I declined to get fully into the reasons why for this, because I didn't feel like turning my article into a more subjective personal take on what I think of these two machines' sounds when playing music. I will say, however, that doing this test and observing the more objective results generated under controlled conditions, did make it basically impossible for me to then go back and listen to the Link playing music and just simply enjoy its particular presentation of the program, when I knew in that in fact it was editorializing the sound more than my reference - however pleasing that presentation might have been with any given disk. JCAudio above has much more experience in this area than a lot of us, and holds a broader opinion of what he's heard concerning upsampling as a catagory. Again, the more folks who attempt this test set-up (how about you, JC?), the more general conclusions we may either be able to come to, or to know to be wary of.
Years ago, long before the advent of upsampling products in the marketplace, I wondered why the same basic process that enabled players to carry out error correction could not be employed to interpolate additional 'smoothing' data points in between the samples contained on the CD. I thought, if a player can generate a reasonable facsimile for a missing sample, or even several in a row, than why shouldn't that technique be used to double or triple the sampling frequency? I couldn't believe that this wouldn't have occured to digital engineers however, so I simply assumed that there must have been some inherent flaw in my reasoning that I was just too ignorant to understand.
Upsampling certainly seems to be the realization of my daydream scheme from back then, so I consider myself to be more than open to the possibility of its unqualified success. And of course, that is precisely why I went ahead and laid out the cash to hear some fruits of the technique for myself, even though you could never accuse me of being an early adopter. I was quite prepared to sell my Basic and keep the Link even if I heard merely comparable sound, because of the Link's more up-to-date input capabilities.
Maybe in the future I will try out a different implementation of the upsampling technique, but I'm not as curious anymore - not because of my experience with the Link, but because of the results my Basic returned. Since my test revealed it to be quite transparent to the source, I consider myself satisfied, for the time being, standing pat with the DAC whose sound I was pleased with when I got it, and continue to be. I'll just listen to it knowing that, if I hear something I'd rather not, it's probably the disk and not my DAC that's to blame.
61, let me address your proposal first: the problem with this is that to listen to such a CD-R, you need to put the signal back through one of the DACs again, or another DAC - you cannot listen to an 'unconverted' signal. So your test would have the effect of comparing a signal that's been digitized and converted twice against one that's been so processed once, which I'm afraid wouldn't be very useful. Remember, in the set-up I describe above, you are not hearing the two DACs [or two DAC modes] pitted against each other, but rather separately compared one at a time directly against the analog feed they are processing the digitized version of. Also, the random component you mention couldn't make your test 'blind', because you would have no way of comparitively evaluating what you were listening to unless you noted the track numbers as they came up, in which case the test is no longer blind (it is generally not possible, for the same underlying reason, to construct a 'blind' test run all by yourself - someone has to be able to take note of which choice the listener is evaluating at any given point in the test, even if that person doesn't know which variable that selection actually represents, in the case of a 'double-blind' test, which requires yet a third person).
Now, if in my set-up proposed above, I had had two identical digital outputs on my ADC, then a friend could have helped me to do a blind ABX test using both DACs and the direct analog feed at the same time, since my preamp does have two tape monitor inputs. As it is, my CD-R recorder has one S/PDIF output on RCA and one Toslink optical, which would have confounded such a test. My Theta does happen to have its own digital record loop on RCA, so I could send a feed to the MSB, but that would introduce an extra digital cable running to the Link. While running the test as a blind ABX would be interesting and valid to do, if you are able to try the procedure I detail above in your own system, I think you will wind up agreeing with me that it is very useful and illuminating in and of itself.
Getting back to your points, Sean, I can't argue with your caveats, and indeed do believe that I essentially acknowledge the main thrust of your comments in my posts: that this test can only evaluate the particular components under review, and should not be construed as an overall indictment of the upsampling technique. It was a provocative result, however, precisely because the other factors affecting the sound that you bring up (parts quality, filtering scheme, power supply, etc.) stayed the same when I compared the different modes (no upsampling, 96KHz upsampling, 132KHz upsampling) present within the Gold Link itself. But as you correctly say, implementation is everything. The observed finding that the Link's output most closely resembled its input when upsampling was defeated is what prompts me to urge others, some with other kinds of upsampling machines, to try and run this test themselves if they can.
Obviously, the only final conclusion that can be drawn from my own experience is that I prefer my reference, but I declined to get fully into the reasons why for this, because I didn't feel like turning my article into a more subjective personal take on what I think of these two machines' sounds when playing music. I will say, however, that doing this test and observing the more objective results generated under controlled conditions, did make it basically impossible for me to then go back and listen to the Link playing music and just simply enjoy its particular presentation of the program, when I knew in that in fact it was editorializing the sound more than my reference - however pleasing that presentation might have been with any given disk. JCAudio above has much more experience in this area than a lot of us, and holds a broader opinion of what he's heard concerning upsampling as a catagory. Again, the more folks who attempt this test set-up (how about you, JC?), the more general conclusions we may either be able to come to, or to know to be wary of.
Years ago, long before the advent of upsampling products in the marketplace, I wondered why the same basic process that enabled players to carry out error correction could not be employed to interpolate additional 'smoothing' data points in between the samples contained on the CD. I thought, if a player can generate a reasonable facsimile for a missing sample, or even several in a row, than why shouldn't that technique be used to double or triple the sampling frequency? I couldn't believe that this wouldn't have occured to digital engineers however, so I simply assumed that there must have been some inherent flaw in my reasoning that I was just too ignorant to understand.
Upsampling certainly seems to be the realization of my daydream scheme from back then, so I consider myself to be more than open to the possibility of its unqualified success. And of course, that is precisely why I went ahead and laid out the cash to hear some fruits of the technique for myself, even though you could never accuse me of being an early adopter. I was quite prepared to sell my Basic and keep the Link even if I heard merely comparable sound, because of the Link's more up-to-date input capabilities.
Maybe in the future I will try out a different implementation of the upsampling technique, but I'm not as curious anymore - not because of my experience with the Link, but because of the results my Basic returned. Since my test revealed it to be quite transparent to the source, I consider myself satisfied, for the time being, standing pat with the DAC whose sound I was pleased with when I got it, and continue to be. I'll just listen to it knowing that, if I hear something I'd rather not, it's probably the disk and not my DAC that's to blame.