Fun Analog Upgrade Challenge

Here is what I hope to be a more concrete way of sorting out what YOU think is the most important component in an lp playback system. Jack is an audiophile and he's really into vinyl. He has a $20,000 stereo system: Rega RP10 ($5,500) Lyra Delos ($2000) Rega Aria phono preamp ($1500) Vinyl system = $9,000, Speakers and amp = $9000, cables = $1000 for a total of $20K.Here's the challenge, Jack is really happy with his speakers and amp, and has listened to much more costlier cables in his system and has decided that he's happy with his cables. He loves vinyl and has $10,000 for an upgrade to any ONE of the three analog components: cartridge, phono preamp, turntable. The $10,000 would be added to the existing amount. So he could choose a $15,500 table, a $12,000 cartridge or a $11,500 phono preamp give or take a few thousand. So you could choose a component that cost a few thousand more or less than these guides but you can NOT divide up the 10K among components - you have to choose ONE to put all the money one.Which one of the three would you choose to upgrade: table, cart or preamp? Which specific component would you recommend and tell us the price and most important -why?I wanted to design this a fun exercise to tease out what would make the most significant upgrade when ALL the components are already GOOD. So often the arguments about relative importance are founded on the assumption that one of the components is bad. "Well if you have a crappy TT..." What if all three are very good. Which major upgrade - pushing that individual component to the $12-15,000 price range, would make the BIGGEST IMPROVEMENT?That's the challenge, what would you do?