In Issue 242 of The Absolute Sound I compared the SuperHiRez.com DSD download of Rickie Lee Jones’ Traffic in Paradise to the SACD layer of the Analogue Productions hybrid disc. At the time, it seemed like a fair comparison. In my setup, the same DAC (a CH Precision C1) can handle a native DSD stream from both my PC and a CH Precision D1 SACD transport. So, same bit format, same material, same DAC—let’s see how these different masters compare! Briefly, the SACD sounded way better.
Then I got a call from Gus Skinas of The Super Audio Center, who had authored the SACD. Gus very politely informed me that the download was taken from the exact same file as had been used for the AP SACD. So now it was clear that I had compared identical bits in the same format going through the same DAC. In theory, they should have sounded the same—but they didn’t.
So what accounts for this discrepancy? As Gus and I discussed the matter, the answer became plain. Although the bits were the same and the DAC was the same, the interface between the DAC and the two sources was not the same. In the case of the hi-res file, the DSD bits flowed over USB. However, when playing the SACD those same bits traversed CH Precision’s proprietary CH-Link interface. I thought I was comparing different masters and preferring one, but all I had really proved was that in a tightly controlled environment, with all other variables held constant, CH Precision’s proprietary DSD interface trounces USB.
Are we surprised? No, we are not. USB has exhibited its deficiencies time and again. Most recently we have seen that DACs which support streaming from a NAS drive typically sound superior in that mode. Now we have learned that USB’s inadequacies do not stop at DSD’s door. I do wish I had clued into the interface factor before dissing the SuperHiRez DSD download. Turns out, it wasn’t the download’s fault at all. To SHR and Sony, I apologize for not coming to this realization sooner.