So my CD player is not transporting the data well enough? Not trolling here, I'm legitimately trying to figure out whether or not a better cdp would transport the data better. Assuming a better CDp would essentially sound better, I'm am sensing the law of diminishing returns with regard to actually using a separate Dac with a higher end CD player.
That's an excellent question - and I wish more audiophiles realized that it is a question worth asking.
There are basically three "things" that matter when playing digital audio:
1) The numbers (digital audio is basically a long list of numbers)
2) The timing (when the numbers are processed - because, in order to make digital audio back into analog, you have to convert the right numbers
AT THE RIGHT TIMES)
3) The actual conversion process (there's actually a lot going on there - but it all falls under "functions of the DAC")
To get the easy one out of the way first, if the numbers are wrong, then what you end up with will be wrong too. Now, all CDs have error correction. What this means is that, if only a few numbers here and there are wrong, maybe because your disc has a small scratch, they can be mathematically corrected
PERFECTLY. The upshot of this is that, unless your disc is badly damaged, the cheapest $50 CD transport will deliver
EXACTLY the same numbers as the most expensive one - period. The only real difference there is that a super-expensive CD transport
MIGHT do a somewhat better job of playing a badly damaged disc without screwing up. (Most of even the cheapest $20 computer drives can play most CDs absolutely perfectly; not "sort of"; not "almost"; they will give you precisely
THE SAME numbers as the most expensive one.
If you're talking about computer files, then you want to avoid resampling, which also alters the numbers (not actual errors - but changes). And, if your connection (USB, optical, or Coax) isn't very solid, you might lose a few numbers here or there (a lot like with a bad scratch on a CD). With computer audio, you're more likely to get obvious dropouts if the data stops for a minute than you are to get subtle alterations. (Note that, when you RIP a CD using modern ripping software, you get precisely the correct numbers. Most modern rippers actually check your results against known checksums. Therefore, those properly ripped CD audio filed are
PERFECT. Not "almost perfect"; not "almost as good"; perfect. And, by nature, computers generally don't give you "more or less the same data you put in" - what you get is usually precisely correct - unless you've allowed some software to "deliberately" modify it.)
The DAC, the last piece in the equation, is actually quite a complicated piece of hardware these days... but we're not going to talk about it here. Some DACs are a lot better than others; a CD transport is simply a CD player without a DAC (the idea being that, since a lot of the DACs inside CD players aren't very good, you'd rather pick your own separately). DACs can, quite literally, cost anywhere between about $1 and about $100k - and the ones you get in cheap CD players tend towards the lower end of that range.
Now, to the part that seems to confuse some people....
In "the old days", DACs simply converted the data they were sent as they received it, so the data source controlled the time when each number was converted. In that situation, if the source doesn't deliver those numbers exactly on time, the variation there will result in a form of distortion. (That distortion is
NOT "jitter"; jitter is the actual variation in timing; but jitter
CAUSES several types of audible distortions. Many people describe the typical distortion caused by jitter as "making the sound blurry".) Old style USB connections were notorious for lousy timing, CD transports varied quite a bit in that regard, and even a funky cable could mess it up a little... so all of those things mattered.
HOWEVER, modern USB DACs use an asynchronous USB connection, which means that the timing is controlled by the DAC and not the source. And many modern DACs, like the DC-1, have internal mechanisms that re-clock the data from the other inputs too (they ignore the details of when the data arrives and use their own internal clock to convert it). In either of those situations, since the DAC is using its own timing, the accuracy with which the source delivers the data at the correct time simply doesn't matter any more. This means that, with one of those modern DACs, since a $10k transport delivers the same numbers as a $50 one, they will sound exactly the same (with that DAC). Likewise, even if you're using a USB connection, which is very different..... same numbers = same result.
Now, since nothing is absolutely perfect, this is a slight oversimplification. For example, the asynchronous USB input on a modern DAC should remove virtually all jitter coming from the computer, but will then add back a tiny bit of its own; and an ASRC (like the DC-1 uses) can't remove
ALL the jitter; it actually just reduces it by a factor of 100x or so at most audible frequencies. (This is still
WAY better than the Phase-Locked Loops old style DACs used; and those were
WAY better than nothing.)
So, the short answer to your question is that, if the DAC has some sort of effective jitter-removal mechanism, then you really shouldn't hear any difference between transports... unless one of them is so bad that it's actually not delivering the proper numbers. And, as I mentioned before, even the cheapest $20 computer CD drive isn't
THAT bad. (On the DC-1, you can turn the jitter-removal mechanism on the Coax and Toslink inputs on and off; and, if you turn it off, you'll be able to hear any differences between various transports or other sources - if there's anything audible there to hear. But, since old-style USB interfaces performed so badly, you're stuck with the modern asynch USB input that works right.)
Note that there are some modern DACs which, due to the way they're designed, may still in fact be sensitive to jitter. (This may be simply due to poor design, or to a deliberate choice to "go retro" and avoid using modern designs with good jitter immunity.)