How to improve Jitter issue via USB/ETHERNET ?

[Confused]

Both USB and Ethernet inputs are already digital so there is no digitization as such in the Devialet.  If you're referring to analog inputs, then you might want to ask Devialet about the level of jitter added during digitization; I haven't seen any measurements.

Both USB and Ethernet are packetised, asynchronous protocols so the audio samples are buffered and clocked into the output path (DAC) by the Devialet's internal clock.  In other words I would argue that the jitter will be entirely limited by the Devialet's clock.  Others may disagree although I haven't seen a coherent explanation as to what might cause additional jitter.

Although the signal is "digital" it is represented as analog voltage levels that are compared against thresholds at the receiver (Devialet).  In principle a digital transmission can be affected by noise that might cause bits to change value; in any normal (to-specification) USB or Ethernet cable in a home environment this should be a very rare event if it happens at all.  In the case of both USB and Ethernet this would cause a whole packet to be dropped because the receiver (Devialet) can detect that the packet is errored.  Normally this would result in easily audible drop-outs.

I don't think this is what people are arguing about when they say that one or other kind of USB or Ethernet cable affects sound quality - rather I think they're talking about more subtle things like (for example) how much noise can leak through the cable into the sensitive parts of the DAC.  Now we're into subjective territory -- in other words, if you are concerned about this you have to try a number of cables and see which you prefer.

I cannot fault your logic Mr Thumb.  That said, I remain baffled by digital audio.  As an example, last weekend I was comparing the microRendu to the SOtM sMS-200Ultra.  OK, this is a subjective comparison with all the perils that this can entail, expectation bias, poor aural memory, and all the rest of it.  There were, subjectively, many differences between the microRendu and SOtM kit, but one thing that appeared to be very clear is that the SOtM kit was brighter than the microRendu, it quite obviously had a little more treble, something equivalent to tweaking the treble setting on the Devialet by about 2 or 3 dB.

Why this should be utterly baffles me, we are talking about a comparison of two devices that feed 1's and 0's to another device (MC3+USB) that then re-clocks and feeds the same 1's and 0's to a Devialet.  The SOtM kit has a very good reputation for filtering noise, the microRendu less so.  So could having more noise via the microRendu lead to a 'darker' sound, or less noise make the SOtM kit brighter?  Plus, this noise needs to make it though the MC3+USB, which itself has clever isolation on it's USB input.  As I said, utterly baffling!