Hi TK,
Yes, of course manufacturers need to differentiate themselves and use clever marketing techniques to do so. Thanks to JohnK for digging up the Boston Audio Society report by Stan Lipschitz of the blind tests of Linn's Ivor Tiefunbrun's nutty assertions about D/A converters as well as the presence of digital watches in a listening room. Speaking of snake oil, Tiefunbrun is a master. At the time of those tests, Linn had a pre-eminent spot in high-end audio marketing its turntable, so of course it was in Linn's interest to put down digital recordings and DACs. Curious how a few years later Linn introduced its own CD players. . !
After those tests, at which I was present, Tiefunbrun made the lame excuse of having a cold, which prevented him from scoring better than chance would have predicted.
When you use an optical connection from your CD player to your A/V receiver, the conversion takes place in the A/V receiver. The optical (or coaxial) digital connection bypasses the CD player's DACs and routes the digital data stream from the CD player's pickup through to the receiver's D/A converters. This connection bypasses the CD/DVD player's internal DAC as well as its analog preamp. The latter may be a source of slight frequency response errors, which, in theory might be audible (unlikely) but going the optical/coaxial digital route is a "purer" sort of connection.
You can't do that with DVD-Audio or SACD, except for some Denon units that have a proprietary connection. And don't lump audio and video digital connections together. Among DVD players, there are visible differences in the video performance of players that do not necessarily correlate with price. Video frequencies run into millions of Hertz, and any deterioration caused by errors in the video D/A converters will be measurable and visible with test patterns. In my experience, they are very hard to detect with movie playback.
With all but the DVD players that have a DVI or HDMI digital video connection, the video signal from a DVD player is analog. This in no way affects its performance as a CD playback device, and, as I've pointed out, audio DACs are a mature technology.
You must interpret my comments in the context of whether or not measurable differences in performance on the test bench using test signals ever translate into audible differences with music. My point about the comparisons of the expensive outboard D/A converters and the inexpensive and expensive CD players (using their own internal DACs) or bypassing them through the $20,000 outboard DAC is that no audible differences existed in my tests. No video was involved. Digital video is a relatively recent development (mid-'90s) with the introduction of the DVD.
There are measurable differences, for example, in the noise floor of cheap universal DVD/CD/SACD/DVD-Audio players and expensive ones. The cheap ones may have noise floors no better than -70 dB, instead of perhaps -90 or -100 dB. Is that audible? Yes, with test signals. Can you hear it with music programming on DVD-Audio or SACD? It's unlikely, but ask me that in a few months when I've done some more tests of cheap universal players vs. expensive ones.
Regards,
