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

glupson - Correct that CDs don't fail very often, the laser is usually at fault. 1 or 2 out of 7,000 CDs made since 1984 have failed me. I make it a point to clean the laser every year (1,000 hours) or sooner. It makes a difference with 80+ minute CDs (London classical reissues sometimes go to 85 minutes).  
Elizabeth and roxy54 - I 100% agree.  The mastering is numero uno in the resulting quality of vinyl and CD.  Just last night, I played Turandot/Mehta on a London CD but when the chorus came in, it was a hashy mess.  I put the LP Decca version on and bliss, full, detailed sound.  (Why do so many of my London opera CDs sound like poor quality remastering compared to the LPs whereas London's mono classical sound superior to their LPs)?  
I went through about 40 used CD players from 1985 to 2000 (mostly average quality/$500-$1500 Denon, Sony, Yamaha, Marantz etc.) until I found the EAR Acute 1 in 2007.  Audio nirvana with NOS tubes and cabling.  My friend upgraded his CD only system with a COS Engineering DAC using a Pioneer Elite DV05 as a transport.  Yes, it's got superior resolution.  I do not have the problems geokaitt claims CDs have with well recorded and mastered CDs.  My sound engineered audioroom cost twice as much as my main audio system but it's worth it (only an external tweak here and there, no big change ever again).  I have friends who are CD or vinyl only listeners.  Funny how they both enjoy my quad  front end system (plus RR and 78s).   CDs are just easier to use than LPs.  

itsjustme I agree.  What bothers me is that my London/Decca opera LPs sound so much cleaner/less distorted than the comparable CDs, most of them digitized in the 1990s (just compare the choral parts of Turandot/Mehta-the CD is distorted).  I don't have that problem with any other classical label (7,000 CDs in my collection).  I have many wonderful 1980s jazz CDs from Contemporary and Japanese CDs.  I also have terrible/awful remasterings of mono RCA opera from the last few years (the 1980s transfers sound 90% as good as the original LPs, the new ones have cut off bass and highs, forward bright sounding mids, compression-yuk!).  Many Amazon reviewers seconded that conclusion.   Luckily, I have many Kevin Gray remasterings of all genres in both LP and CD formats.  

For my listening pleasure, I spent a ton of money on my listening room/acoustics.  Next is the cost of my analog front end.  Digital front ends can sound great even if they aren't expensive nowadays, unlike the 50-75 CD players from the 80s and 90s that I tried.  Speakers are very important in the chain and lucked out using great older speakers rather than new ones at a pittance of new price.  I get SOTA cabling from a manufacturer as a beta tester and the rest of the electronics are custom made at a low price as well (my second CD only system costs $5k yet sounds better than 90%+ of audio show gear-simple but perfectly matched tube gear and 25 year old speakers).  

Matching good sounding components is the key to good sound after accounting for the big elephant in the room-the room itself.  I use Hallographs and SR HFTs to tune the room perfectly.  Those are items generally not found in audio shows or audio salons.  Too bad as their cost relative to their merits is well worth it.  One can use lesser equipment in a great room but ruin great equipment in a poor sounding room.

My two bits.

My electronics/cabling manufacturing friend got a COS Engineering $3,000 DAC that blows away my EAR Acute which is twice the price.   It took about 13 years since I purchased my CD player for me to hear the improvement in a DAC since most under $5,000 DACs I've heard are no better (and sound less analog-like) since 2006.  The COS unit is remarkable (based on a slimmed down $10,000 pre-amp/DAC unit).  Amazing and affordable compared to the high end DACs costing $10-50,000 I've heard at shows.