Time to upgrade the pre-amp.

There is no way SP-11 main preamp stage has 75dB of gain.  Not sure what its main preamp stage has.  I don't have a PX25 here but have a diavolo which is a very similar amp.  Just 300B instead of PX25.  

I have tried it with a myriad of preamps and it sounds best with no gain but is fine so long as gain levels are in single digits.  You are okay with 6dB.  0dB is better but the matching preamp is uncommon used and new is $8500.  I think above where you are looking in the used market. 

I have one arriving later this week or early next week and am in central jersey if you want to arrange a demo.  

Seems to me you're a pretty experienced audiophile and already have a pretty solid sense of direction. You might just want to go with the options you're already considering.

I think you've got some good recommendations. And I'll add another, below. One thing I think you should consider is whether the equipment you buy is hard wired or employs the use of circuit boards. For myself I prefer point-to-point wiring and tend towards small, boutique or semi-boutique specialists. 

Consider that probably much of the advice you'll receive (including that which I am about to give you) will be heavily biased in favor of the equipment that the person giving you the advice owns. Let's not "call anybody out" for this, like there is an intention to deceive. I think it's reasonable to simply recognize it. In a way, it should provide some confidence that those who are chiming in here at least have some familiarity with the equipment they're talking about. Consider, though, that probably nobody has been able to compare all the options being discussed. And even if they had, their listening preferences might not be the same as yours. And, of course, the context of your system is what really matters.

Having said all that, I recommend a Supratek. If you do a search for "all time most popular threads" you'll find the "preamp deal of the century" thread, which is now approaching maturity, as it is almost 20 years old. One of the things that attracted me to Supratek was the fact that many who posted on that thread had previously owned many of the well-respected brands we are talking about and felt that Supratek was sonically an improvement over what they owned before.

But whatever you go with I expect you're in for a fun change.

First of all, I misread the SP-11 gain. looks like 29db if I am reading this right: https://www.arcdb.ws/model/SP11.

@markusthenaimnut thanks for the comment re "experienced audiophile" but I am afraid you are mistaken. Perhaps "old audiophile"... that said I am attracted to P2P vs printed boards. Instinctively I think the former is better. My Icon Audio phono stage also fits that them. With ARC, i must admit that I appreciate the polished presentation, the copious documentation and the ready resale market.  That said I will be taking a detailed look at Supratek. @verdantaudio, is the matching pre-amp for the PX-25 the Conductor Simply? I think I saw it had no remote and stopped looking, but I will take a deeper dive.

Conductor Simply 2 and it comes with a remote.  I don’t offer the non-remote version as no one really wants it.  Mine is literally in-transit from UK.