I can hear the difference between some DACs. I would not put them in a category with cables.
Me too.
In the late 1990's I heard a very obvious difference between sample rate clocks with the same converters.
An Aardvark time clock was a system upgrade at the time.
My now about 10 year old MOTU 828mk3 interfaces sound better at HD sample rates than SD sample rates.
To the point where you can upsample something SD to HD and it sounds a smidge better. (I do have a smidge meter.
)
My now about 10 year old Apogee converters sound just as good at SD as they do at HD. Which is also noticeably better than the MOTU converters sound at any sample rate.
The apples to apples test is to digitize a vinyl album FYI.
The telltale sound of the less stable clocks from almost 20 years ago is the depth of the soundstage collapsing. Not as smooth or open high end. Already getting subjective here and inducing eye rolling...
Ever heard a stereo pair of speakers just sloppily not aimed properly? Randomly pointed and/or un-level vs each other? Know how the phantom center pretty much disappears with that vs setting them up right? Pretty apparent in a more audiophile setting. Might still not even notice with Worst Purchase fare.
That's the level of smear I'm talking about from clock jitter.
Converters that don't perform as well at SD sample rates (literally the reason HD exists) tend to have either a reduced high end from sample rate filtering cutting into the high end of the audio band or a bit of an edgy sound from distortion from the sample rate filtering. HD avoids this passively by giving a wide margin between the audio and the sample rate. The boutique converters have more precisely dialed in filtering at SD.
So I hear these things.
I especially hear things when audio has already had some damage. Generation loss (be it analog or digital) stacking up leads to all sorts of unexpected things.
I hear things getting better as I tried to describe in my progression through gear.
I still think that actual mix prowess and mastering handling account for 95% of what anyone hears when they hear something they need to talk about.
Cable funny business vs converter funny business?
Cables are more obvious. PROBLEMS with cables are more obvious I mean.
A poorly crimped wire in a connector or a layer of oxidation in an analog cable causing a 2 or 3db signal drop.
A poorly made shield that doesn't cover the wires inside 100% (best shielding is full braided plus foil shield) and/or broken shielding letting in noise.
A digital cable with connection or shielding problems resulting in dropouts resulting in either static popping in the audio or the device silencing itself.
Doing something stupid like using thinner than 16AWG wire for speakers. (Some would argue 12AWG minimum.)
Once the connections are good, they all sound perfect to me.
Converters differ like I tried to describe.
The other part of the converter unit that can vary is the analog part. AD converters have analog components on the input. Go cheap on that and you digitize already blurred audio. DA converters have analog components on the output. Same deal. So you'll hear differences between different equipment that uses the same digitizer chips.