Where is the significant point of diminishing returns on hi-end turntable?

With a member name of porsche and a $25K analog budget, you’re way out of my league. However, to answer your question, "Where is the significant point of diminishing returns on a hi-end turntable?," I would say that $10K is about all I want to spend on an analog rig (VPI table+Parasound phono stage+quality cartridge). Buying used would allow me the most value. You will probably get as many opinions as there are members on this forum. One man’s ceiling is another man’s floor!

your post brings back memories from my earlier days in this obsession. I remember buying the Dual 701 when it first came out and my Sansui receiver and a pair of Bose 601(yeah, didn't know the jingle bout BOSE back then) and thought, hey this is pretty damn good. The Dual was well respected in its day and Sansui was considered a good brand. 400 dollars for the Dual back then was a pretty high price for a turntable but i thought i had arrived. OVer the years i have had that feeling several times after discovering a new toy. From Dual, to Denon, Mitchell, and finally working my way up the Maplenoll line to the Apollo. I guess i am saying, enjoy what you have but keep looking, trying and getting surprised. Its not always how much money you can spend (and you can spend as much as you have on this hobby), its more how you match and fit components together with your listening tastes. I really never knew how good High Fidelity could sound until i put the needle down on my first Maplenoll. I now run a ZYX Universe II on a Maplenoll Apollo feeding a RCM Sensor II Phono through a Pass xp10/xa30.8 powering my AudioPhysics Caldera II speakers. I think this is the final configuration, but----. 
All this being said, with 10-25K, you should be able to put together a reference vinyl system that will please for a long time. But there will always be something better. 

Oilmanjojo has this in good perspective, imo. The question I would pose to you is: Do you hear the difference and is it meaningful to you? Then, does making that step from the $10k rig to the $25k rig still allow you to have a superb phono stage? Amp? Speakers? Cables? Or would you have build a BETTER sounding system overall by stepping back a bit on the investment in just this one part of your system?

Over the years that I've invested in this hobby, I've always found the investment to be a stair step process. I HEAR more of what's going on in the rest of my system as I upgrade in an area and then assess what will make the next biggest improvement. But I have always planned on DOUBLING the investment in each step up that staircase. Small incremental steps just keep shunting money down a tube that never stops draining cash but without providing material improvements in sound.

All this said, as Oilmanjojo suggests, "with 10-25K, you should be able to put together a reference vinyl system that will please for a long time. But there will always be something better."

But if you're making that next big investment, and if you are seriously committed to vinyl, then the best place to make that investment is in the turntable/arm/cartridge front end. What doesn't get extracted from the vinyl to begin with is never heard in the rest of your system.

I'll close with one final observation: The magic is in the details. Scrupulous attention to setup, to fine tuning, makes all the difference between superb playback and indifferent sound. You can often get far better sound than you ever expected if you really understand what is needed to finely tune the setup of a vinyl front end and take the time to do it. 

Good feedback gents. 

I see what you mean rushtton about identifying holes in my system. I need to improve my power cables next. Using all stock power cables except for one Ps audio 12 something or othe. Getting closer with each new component. Unfortunately I'm on 10x path versus a doubling but damn this is fun. 

Listening to the entire wall album now and drinking some fine red wine. Life is good. 

And I'm assured of a true reference setup from  the dealer. Clearaudio innovation wood, Benz cart and aestetix rhea Sig phono. It should match well with my new voxativ gear. Fingers crossed.