Hi-Fi+: What do you see as the comparative merits of higher-than-CD resolution PCM, DXD, and DSD digital audio file formats? Which of these formats do your top products support and why?
CH: The only reason to support any format is for the content that is available. A new format could be developed that would out-perform anything available today, but if there is no music available it would be meaningless to support it.
It's easy to make a higher resolution format. We can have a fabulous musical experience from an analog LP. One can also purchase 45 rpm 12" vinyl that sounds even better. Does that mean we should then develop 100-rpm records? Where do we draw the line? There is a point of diminishing returns — just because you can do something doesn't mean you should.
I would rather have an incredible sounding CD player than an excellent sounding high-resolution player, simply because there is a vastly larger music library available on CD. Given the reality of where the content is means that it is far more important to deliver an exceptional experience from 44/16 than anything else. If one understands how to deliver a truly emotional experience from 44/16, it isn't that difficult to do it with higher resolution formats as well. "God is in the details, as well as the devil". Implementation is everything, and I would far rather listen to a lovingly made standard resolution recording than a carelessly made high resolution one.
DXD is simply high-resolution PCM, but it may well have gone past the point of diminishing returns. Much more importantly, how much content is available in that format?
DSD is a different story altogether. DSD recordings almost universally sound superb. It is also (as former Philips senior engineer Bruno Putzeys points out) "a phenomenally clumsy" format for recording. In my experience, part of the excellent sound of DSD is the format itself and part comes from the fact that anyone willing to go to all the trouble to use it will make sure everything else is also done properly.
Ayre's approach is to understand exactly what it is about DSD that allows for its high level of performance. And it certainly isn't what we were told it was! It turns out that it is really in the time domain, which is no surprise when we understand our marvelous ear/brain hearing mechanism. Once the principles are understood the question becomes, "can this knowledge be applied to PCM?"
The answer is "yes" — perfectly so for high sampling rates, and much of it can be applied even to 44/16 as well. The result is the superb sound quality of DSD, while avoiding DSD's problems arising from out-of-band noise, plus the ability to use standard tools and techniques in the recording studio. When the widespread content of the CD is factored in, DSD can be seen to be much more valuable as a learning tool than a format per se. Of course there are now thousands of wonderful sounding albums available in DSD format, so it is important to support it and not limit the choice of music that can be played.
Hi-Fi+: Consumers can potentially deliver digital audio files to their systems in a number of ways. How do you assess the relative benefits of streaming devices, dedicated music servers, or PC-based servers—especially in terms of sound quality?
CH: My experience is there is generally an inverse correlation between convenience and performance. AudioQuest does a seminar demonstrating the sound quality of a DAC connected to the data source with Wi-Fi versus connecting with a standard cable. It's not hard to imagine that if a higher quality digital cable can affect the playback quality that going to wireless is a big step backwards in performance and that is exactly what the seminar attendees experience. Yet wireless is certainly convenient...
All of this is still in its infancy. It's taken decades to achieve high quality sound from digital audio. Computer-based systems still have quite a way to go. Why do various bit-perfect file formats sound different? Why do different USB cables create a different musical presentation if one is using an internally clocked asynchronous DAC with galvanic isolation from the computer? These are just a few questions and there's still a lot more to learn.
The fact that there are three or four different ways to store and deliver digital files is proof that none of them are perfect. They all exist because they offer different trade-offs, often in performance versus convenience. And as with all new technologies, things will have changed significantly in five years and yet again five years after that. I have no doubt that in the near future there will be new ways to deliver music that transcend today's limitations.
Hi-Fi+: If you are at liberty to say, what will be the next digital audio products from your company, and when?
CH: Ayre has just introduced our Codex USB DAC + headphone amp + preamp. The real breakthrough here is bringing an unexpected level of musical connection at a much lower price than before. The flip side of this means that we have also learned how to push the limits of what is possible when the cost is not so tightly constrained.