Good explanation here on the Linn forum:
http://forums.linn.co.uk/bb/showthread.php?tid=23096Fantastic interview here with John Siau of Benchmark media about the limitations of DSD and why PCM is superior.
http://www.realhd-audio.com/?p=74Favourite quotes:
JS: ...With 4-bit delta-sigma converters we can now achieve a 130 dB SNR. This is a full 10 dB better than the channel capacity of 64x DSD. A 1-bit system simply doesn’t have enough room in the format for both dither noise and the audio signal. DSD is limited to a 120 dB SNR over the audio band. You can pass an audio signal that’s partially dithered or an audio signal that has no dither but there’s not enough room to pass a fully dithered audio signal. You need more than 1-bit in order to be able to do that.
JS: I actually had a SONY engineer say to me one time and this is quite few years ago…he said, “we realized after we got a ways down the road that DSD was kind of a mistake but we had too much invested in it”.
MW: Wasn’t archiving their whole reason for coming up with it in the first place? It was going to be used to take their analog masters in their vault and putting in a format that they thought would preserve the most fidelity, right?
JS: Yeah. And conceptually it looked like a simple approach. And, DSD significantly outperformed the 16-bit PCM systems that were common at the time. As a distribution format, DSD is definitely a big step above 44/16 CDs, and we want to give people the best possible playback of the wonderful DSD recordings that already exist.
MW: And they tried to put in the successor to the CD and that’s where we got a format war.
JS: Yep. Moving forward, we should focus on 24/96, and 24/192 downloads as these formats offer the best quality available.