What Sonically is the Difference between a $1,500 CD Player and a $10K-$25K One?

So much to say here. I’ll avoid the direct comparison because that is very brand dependent and no one has heard most stuff. but the question"what makes one better" is, to me easier to answer. A CD player, end-to-end has many components, and many of those are analog or have analog components - including those before the DAC!

My broadest comment is to migrate from CDs to files, and play them out over USB. For me, using ALAC/FLAC, either ROON or Bitperfect streams sound substantially better than the original CD - played through the same DAC and equipment. In my experience, the best sound and lowest noise  requires running my streaming hardware (and OLD macbook pro) from its battery, not plugged in, sigh. Why better? Likely jitter. A CD transport following the standards probably puts out SPDIF, and a cheap transport - or even a good one - will have some timing degradation.

Note as i have blogged about, SPDIF makes the source (e.g.: that cheap-o CD player) the clock. Your $10k DAC takes jitter form the source.  USB turns this around and simply sends bits to a buffer, where they are re-clocked by the DAC, or can and should be.

Once you have the bits in the DAC portion of the chain one must re-clock very precisely and eliminate noise, both of which contribute to jitter. Jitter, changes the X-crossing point of the reconstructed musical wave and therefore is a plain, old analog distortion. no audiophile magic necessary here. next come all sorts of noise and power supply related opportunities for distortion and of course, the reconstruction filter and analog preamp that is the end of a DAC’s internal functional chain. So if you think capacitors, preamps etc make a difference guess what, you have several of each in there. They must be good.

Bottom line, there are lots of places a transport and DAC can mess up sound. The chip architecture, which most focus on, is probably the least.

Now, just to contradict myself, i have four DACs and have had the chance to borrow several more in my very revealing system. From a Schiit Mido3 (the best $99 DAC i can imagine) to a Theta DSPro/G2 to a ridiculously re-worked MSB (all rework my own designs) these do NOT sound the same - so the comparison of the cheapo to the Theta simply proved that someone can’t hear or has a mediocre system. Ar these differences night and day, awful vs glorious? No! That’s a huge issue in this field/hobby, crazy exaggerations. But the differences are real and manifest themselves even more over long periods of time. My gold test is always "can I go back without missing component X?"

BTW i heard the effect of a $40 amazon sourced Toslink-to-coax SPDIF adapter. You just cannot imagine ho distorted it was. and I have pics of the resulting, ugly wave when i used it in a test jig with test tones (files) and a ’scope. UGLY! Clearly visible jitter to the naked eye! Step function jaggies in the sine wave! Ugly!

Hop this helps
G

Elizabeth said: "Well MY digital is great, and so is my analog."
Voice of reason.
Some of my digital -- even redbook, is glorious. Much of it is terrible. Some of my albums are glorious, some are terrible. HUGE POINT HERE - often its the SAME recording that is glorious in both formats. Case in point: "Ella and Louis", Verve recorded with two mics onto a Studer A-77 in like 1961. Recordings matter. Mixing matters. remixing and digital masterings matter. Format, to me, is less important if all the above are done correctly. Sadly, they are not, and early digital recording, mastering and pre-eq was just terrible. No mystery why those sounded as they did.

KEY POINT #2: both formats are capable of excellent sound. Perfect? Of course not. Neither are LPs.
Now, back to the OP’s question - which was basically around the incremental value from $1500 to $15,000. This is a subjective matter, and a slippery slope. Just as racers inevitably wind up with dedicated race cars, trailer, trucks, etc., so many audiophiles wind up with crazy-costly systems. I only hope they are well chosen and enjoyed. but its likely not necessary - I’ve heard very good sound from iTunes, Bitperfect and a Schiit BiFrost Multi-bit.
Above i noted where some differences can certainly exist. I’m currently evaluating how to hit the 80/20 rule on many of them. My personal opinion is that the biggest differences today, especially for the dollar spent, come from speakers and sources, both analog and digital. You can get really, really good electronics for more modest spend (note: i design and [hope to again] sell electronics, I’m stabbing myself in the back).  Note that "modest" might range form $1000 - $6 or 7k, and some speakers are very challenging loads, while others can be driven by an NAD 3020 (like Vandy 2s).   While cables no doubt impact sound i find the benefit/$$ ratio wildly bad - better spend that money on speakers or DACS (or a great TT/arm/cart). Oh, that’s still a tough area of electronics - RIAA stages for low output cartridges...