SACD is not on DVD media - I don't where that came from.
Of the different encoding systems used (DSD of SACD vs. PCM of DVD-A) DSD (SACD) seems on paper to be the most attractive. It's a much more "natural" representation of the sound, almost analogue. You can look at a DSD bitstream and more or less draw the analogue wave form that made it by hand. PCM (the same system as used for CD) is somewhat more involved.
DVD-A encodes at 96kHz/24bit which is a lot more than the 44.1kHz/16bit of CD but the principles are identical. Both the encoding and decoding of PCM require extra steps that aren't required for DSD. At it's simplest a DAC for DSD can be just an analogue low pass filter
In overall resolution terms DSD is slightly better. It uses a 2.88Mhz sample frequency for 1 bit (delta sigma) samples. I don't know if it's correct to do this but if you divide that by 24 (the 24 bits of DVD-A) you get 120kHz which is higher than 96kHz.
I won't hide the fact that I'm an SACD supporter in the format war for various reasons despite having never heard either. As to which sounds better, clearly I can't comment from personal experience but I've heard equally good reports of both. The lesson seems to be that there really isn't that much between them in the sound quality stakes and the much more important thing is getting the recordings right.
From a purists point of view SACD will always be better. Since most (all?) digital recordings are done with a 1bit DSD ADC anyway why not just stick that information on the disc instead of having to go through a decimation step to get to 96/24 PCM first (and then having to reverse that step in the consumer DACs)?
The unfortunate issue though is that DSD is harder to edit so many DSD recordings are converted to 96/24 PCM anyway for editing so any advantage that DSD had is lost. The same is true of many universal players which convert DSD from SACDs to PCM before doing the analogue conversion.
One more thing, I think it's indicative that the heavy hitters in the audiophile scene (Krell, Classe and others) are bringing out SACD only players. Personally, I think that SACD is close to getting winning the format war. If DVD-A can't get reliable hybrid discs working (so far they haven't) then the format is a dead duck.
Michael.
