Jitter reduction, best device?

Jitter is noise in time domain. Jitter produces sidebands at very low levels but audible since not harmonically related to root frequencies. Jitter free sound has more clarity (free of noise).

Many CD were made from poorly digitized tapes and contain A/D converter jitter that cannot be removed.

As for device - Benchmark DAC1 does excellent job with jitter. Its jitter bandwidth of only few Hz translates to about 100dB of jitter suppression at few kHz.

Jitter comes from recording, transport, cable (reflections on impedance boundaries and noise) and DACs clock jitter.

Asi_tek - Upscaling, also called asynchronous resampling is not bandaiding. It is instead (and not on the top) of traditional extraction of data.

In typical CD-player, as far as I know, stream of data coming from the laser has jitter and varying frequency. Phase Lock Loop is used to sync DAC converter clock to average frequency of the data stream. I believe that now they use double PLL to improve response and FIFO buffers to provide more stable DAC clock.

Upscaling reclocks data with asynchronous clock of much higher frequency. Benchmark DAC1 does manipulation of data equivalent to 1 million times oversampling making DAC clock accurate to 5ps. DAC1 also has PLL but very crude and fast - just to get input data.

Typical CD player has some analog circuitry that mutes the output in between tracks or during invalid data. This circuitry is audible according to some users who tried to disable it. Benchmark detects valid signal and does muting in digital transmitter chip.

Mapman

"If it works, who cares how it did it?"

That's true - but understanding helps to narrow search. Sounds of upsampling, oversampling and non-oversampling DACs are different. Many people don't like sound of upsampling converters (Muralman - are you there?) while I praise clarity and transparency of Benchmark DAC1 and would look for similar one in future. Understanding what jitter is and how to prevent it helps as well.

There is nothing wrong in understanding!