@mdalton
I didn’t attribute the difference to noise. I suggested that noise may be part of the equation. A subtle, but important difference. I did, however, suggest that the difference may be due to the rise and slope of the analogue waveform representing the 1s and 0s. A “bit perfect” file may be interpreted differently because of these minute variations.
Accordingly, I am skeptical of claims of certain DACs to be “immune” to jitter when the benefits of improved clocking are plainly audible. It turns out the ear is astonishingly sensitive to jitter distortions. Again, the benefits of femto second clocks are well known - and the results plainly audible to even not well trained ears.
I would modify your metaphor thusly. Put poor quality fuel into any engine - regardless of the quality thereof, and see if it performs to spec.
You believe what you believe - and have provided some anecdotal evidence to support your claim - which I fully accept. I and some others believe differently and have provided anecdotal evidence to support our belief as well.
I would offer this. We’re still early in streaming relative to high performance audio history. We don’t currently know everything. It was originally postulated that CDs would provide “perfect sound forever” and that, because it was digital, all CD players (and transports particularly) would sound the same. That has been shown to be false, though perhaps still disputed by some who fail to do the work.
Perhaps as an experiment you could try different inputs into your DAC. Try S/PDIF vs USB. Try different cable companies. They are all providing the same bit perfect stream, yet each will sound different. Those differences are measurable, though not necessarily quantifiable. They may not be massive differences, but they exist. This is because digital data is transmitted in an analogue wave form and cable geometry influences that transmission and introduces jitter.
If you struggle with this test - then let’s exaggerate it. Try an analogue RCA cable in lieu of a 75 ohm digital cable for your S/PDIF connection. It will likely sound thin and cast a steely glare over everything, all while transmitting a bit perfect file. Jitter.
Further, noise may not be primary, but it is an issue. All cables are antennas of some sort - both transmitter and receiver. Some are better insulated against this, but all are antennas of some sort. Computers tend to be noisy w/ EMF and RFI emissions from cheap power supplies and lots of other operating components not specific to audio. That’s why dedicated streamers with more attention placed on power supplies, etc. tend to outperform even high end computers. For instance, I had a souped up Mac mini dedicated as a streamer/server. 16 GB ram, solid state drives and everything not related to my music library turned off. That was its only function. It was handily outperformed by a modest streamer. Call me a fool or deluded if you wish. I wouldn’t go back to it.
