Digital Drive: More on Benchmark and Transports by Jim Thomas

I thought people would be interested in seeing Benchmark's explanation of why the DVD player would sound different from the CD player when used as a transport for the DAC-1. This makes sense and is based on engineering as opposed to speculation. Based on this plus my own experience, I would have to recommend not using a DVD player as a transport.

Here are Benchmark's comments:

1) The digital outputs on many DVD players are not bit-transparent when playing CDs.
2) The digital outputs on most DVD players are not bit-transparent when playing 192 kHz DVD material.
3) The digital outputs on most CD players are bit-transparent (I have not yet seen one that isn't).
4) All error-free, bit-transparent transports will sound identical through the Benchmark DAC1.
5) The optical, coaxial, and XLR digital inputs on the DAC1 will produce identical results.
6) The DAC1 is immune to jitter on the digital inputs.

Given the above, any DVD player should be considered highly suspect when playing 16-bit CDs through it's digital output. An older CD player (such as your Denon 1560) is an excelent transport for use with the DAC1. A DVD player may subject the digital audio to poor quality digital processing. This processing may include digital gain control, digital filtering, poor quality sample rate conversion, truncation, redithering, or any combination thereof. In some cases the more expensive players use more processing. Unfortunately there is a total lack of any detailed information from the manufacturers. We have run our own tests on about 10 different DVD and CD players. All of the CD players tested were bit-transparent, and only one of the DVD players was bit-transparent. To date we have only tested a small sample of the players that are available.

Consider your CD player innocent until proven guilty.

But ...

Consider your DVD player guilty until proven innocent.

-John Siau