IME differences heard with different cables is expectation bias, or placebo effect.
I tested this myself and cables I was sure were better no longer sounded different when I got my daughter to change them and I didn’t see what she was doing.
I hear differences between microphones I use, I used to hear differences between the tape recorders I used to use but since I have recorded with digital not only does the recording sound exactly like the microphone feed (it never does with tape) but it has for 30 years since I first used a StellaDAT.
Certainly high levels of jitter give poor fidelity but the only devices with very poor levels of jitter I have seen reviewed recently have been the spectacularly expensive Metronome devices where I, perhaps unfairly, suspected the reviewer heard a difference but since the product was super expensive and nicely styled assumed since it was different it must be better. This seems to happen a lot.
What you consider super-expensive and what I do may be worlds-apart I'm afraid. Most of my customers have systems starting at about $30KUSD. Most have speakers alone that cost that. Many consumers think that they can achieve great SQ with a mid-fi system, but it's extremely difficult. The levels of distortion and compression of active preamps and most SS amps are just too high and they tend to mask out the benefits of good cables of all types, including digital, power and analog. These cables all make a difference if they are well designed and use good materials. Therein lies the rub. There are a LOT of non-professionals in the cable business, even the big names. I often see the same design being used for an analog interconnect and a speaker cable from the same company. This is a dead giveaway that they don't understand the physics of the two scenarios and that they demand entirely different designs to be optimal. I don't design and sell cables anymore, but I know this for a fact: cable design is an art-form because it goes well beyond the L, R and C measurements. The best sounding cables contain conductors that have uniform molecular structure, like properly annealed pure silver or gold. These are going to be expensive by definition. Early on, I did an experiment with silver interconnects. I built two identical sets and then immersed one set in liquid nitrogen. The L, C and R measurements were identical between the two sets after one was immersed. The sound quality of the immersed cable was terrible. Totally unlistenable. This was due to the broken crystal lattice of the silver molecular structure. I did a TDT of the cables and here it is:
The red trace is the immersed cable. As you can see, it has a lot more bumps and spikes because the signal is reflecting off of the broken crystal lattice boundaries.
This proves that the molecular structure of the conductors is important, almost as important as the R, L and C.
Most audiophiles believe that their system is very resolving, when in fact only a very few systems on the planet are truly resolving. My system is one of those. I can easily hear the difference between ALAC, FLAC, .wav, AIFF and other formats playing the same track. I can easily hear offset errors in a given track compared to the track with no errors. This is the quality of system that is needed to design the very best audio products. The last change I made to the Synchro-Mesh reduced it's measured jitter from 22psec to 7psec. I could easily hear this difference in my system. All of my customers also heard this difference.
Steve N.