upscaling, bits and resampling ??

Read my test report on forum in a new post titled Upsampling Put To The Test...it should show up there later today. Look when you have some time, it's a long article! :-)

Different companies have different engineering approaches to how to get the best sound from CD. Regardless of what approach is used, no more information than the 16 bit/44.1KHZ data density that is on the disk itself can be extracted or manufactured by any player.

Beyond that, all I can say is that upsampling, oversampling, straight sampling, multi-bit data conversion, one-bit data conversion, increasing word bit length, reclocking jitter-reduction, data buffering jitter-reduction, adjustable dithering, aggressive filtering, gentle filtering, no filtering, adjustable filtering, single-ended DAC topology, differential balanced DAC topology, active current to voltage conversion, passive current to voltage conversion, S/PDIF input, AES/EBU input, proprietary input configurations, balanced output, single-ended output, tube-buffered output stages, transistor-buffered output stages, etc. - they all have their proponents and detractors. But it is possible to build a good- or bad-sounding DAC or player using just about any of these approaches.

The quality of the implementation is as important as the design approach. This also includes such mundane concerns as transport and laser mechanism, power supply, sheilding, parts quality, mechanical isolation, and even the display readout and remote control. So try to audition some components within your budget that you are interested in with your own system (or at least try to hear them at a shop or a friend's place), and remember that sonic differences between digital components are often subtle in nature compared to, say, different speakers or amplifiers, so be prepared to listen at length, and try to to do direct level-matched comparisions if possible.

I wish there was a way I could tell you what specific configuration to look for that sounds the best, but it just doesn't work that way, so don't get too hung-up on the buzzwords and technical jargon. (Also, beware of players that "make all disks sound good" - lots of CDs actually don't sound that good, but a player that euphemizes the sound too much rather than telling you the truth will impose a sonic signature on all your disks that will eventually become wearisome. And good power conditioning and cords often help digital front ends the most of any sources.) Your ears will know!

P.S. - Take into consideration whether you will want a machine that can decode formats other than regular CD when choosing your player or DAC of the future.

If I'm not mistaken, I believe that the multiple concurrent sampling technique that Marakanetz and Jeff refer to above is actually descriptive of *oversampling*, rather than "upsampling", which has more to do with Jeff's reference to the use of alogrithmic interpolation to synthesize "extra" samples in between the data points to "smooth" the sampling frequency. Both of these are distinct from the adding of extra bits of random dither to "extend" word length from the 16-bit CD data to 24-bits before it is fed to the DAC chips, which is done in an attempt to better linearize the chips' low-level performance. Again, to the best of my (admittedly limited - thanks, Sean!) knowledge, neither of these techniques can actually increase the resolution of the recreated analog signal, but are efforts to extract more subjectively pleasing results out of the digital-to-analog conversion proccess. (I do promise to read that link, Sean - I hope it doesn't show me to be too far off base here!)

I will add that I recently bought a newer generation, popular "upsampling" DAC to audition against my well-regarded older unit, which does only tradtitional oversampling. While I found that upsampling did indeed change the sound, I contucted a controlled test which informed me that - at least for this particular DAC - the results were actually less faithful to the digital input signal it was being fed when upsampling was engaged than when it was defeated. I also wound up preferring, and finding to be most accurate, the performance of my reference model. I intend to write a full review of these sessions and post them separately here on the forum soon, but this experience did once again drive home the fact that it's not the type of technology used, but its implementation, that will often make the biggest difference in performance.