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

My 2010 CDP sounds great which at the time cost 1K~1.5K. I have listened to TT and other CDP setups costing 10K, 20K, 30K, 40K, and even more and I am very happy with my CDP setup. The new model of this CDP costs 1K more but I haven’t listened to it as yet. Guess I am happy with my current CDP setup, although the CDT (a cheap Sony unit) could be better. I also have an older 1996 CDP setup (cost about 4.5K) which is also sounds great (perhaps a little better with less features). So I have been enjoying CDP/digital since then and I listen to a variety of music genres. I also have 3 TTs but rarely listen to them. The source and source setup is your choice and it is good to have choices, enjoy.

There's no difference between a $50 and $5,000 one, except for the fancier box.

One assumes you must have blind tested them, yes?

A good signal processing engineer, if they are truthful, will tell you that all decent modern CD players have little difference in measured signal output characteristics. Modern analysis gear can measure things you could never hear. However, things like dynamic range and other characteristics do vary. I doubt very seriously there is any significant audible difference between $1500 and $25000 players. Build quality, looks, etc, sure. I work in defense and we use A/D -D/A converters, quality amps, etc, all the time. Modern devices are cheap and perform extremely well. I suspect the truth is (and I’ll get flame sprayed) you are paying a huge markup and the cost of low production quantity components, rather than greatly elevated sound quality. I don’t profess to have golden ears, but I can hear differences in some gear readily. But when you get to a certain level of quality (meaning not Target level components) there is precious little difference in electronics. I do not include speakers in this since they are both “instruments” and components and can have unique sound qualities.

What's the difference between a $2 cigar and a $10 cigar?

Exactly $8.