Looking for 5AR4 rectifier tube most like solid state

I've had a SLP05 for a few years now (at least three, if I remember correctly) with the Ultimate Upgrade, and I love the sound of mine.  I'd go so far to say as it may have been the most significant upgrade I ever made.  Unlike you, I am not finding mine to be sweet/warm/colored . . . if anything I find it to be a tad more neutral than I might like, but the detail and imaging I hear with it in my system makes up for that (for me).

I have rolled a few rectifier tubes and I, honestly, cannot say for sure I heard any difference.  I've had a Mullard 5AR4 in there for a while now.  The tubes I've heard the biggest difference with are the two balanced input tubes.  I've had a few I liked (a pair of KenRads a generous individual bestowed on me) a pair of Tunsol VT231s I liked a lot, I loved a pair of black glass RCA VT231s for the precise detail that I thought they brought out.  At the moment I have a pair of "'52 Sylvania Bad Boys" (6sn7s)  (that were described to me as the "Iron Fist") in those sockets and as of now they are my favorites.  Another generous individual turned me on to those two Sylvanias  also gave me a pair of National Union 6F8G that he described as "The Velvet Glove" and I like them, but for different reasons than I like the "Iron Fists."  If  you decide to try 6F8Gs, you will need adapters.

Good luck.  I hope you can get that pre to do what you want it to do for you.  People have different goals and expectaions from their gear, and, as I just typed, I hope you can meet yours.  

. . . I just thought of a similar thread (questions about 5AR4 for a SLP05) a while back ago.  It may or may not be helpful to you, so I'll post a link to the discussion:

5AR4 for Cary SLP05 thread

Thanks for those recent responses. I haven't got that Mullard rectifier yet (picking it up this weekend), but someone came by with some NOS Sylvania 6SN7 GTB. That was a big boost forward, beyond the Electro Harmonix (Gold in the Input, and regular in the Driver).

It's getting closer to "good enough". We'll see if the Mullard takes it over the finish line. Otherwise, a pivot to another preamp may be required.

It’s getting closer to "good enough". We’ll see if the Mullard takes it over the finish line. Otherwise, a pivot to another preamp may be required.

Good luck in those regards.  Let us know how it goes for you.   I have read posts from both sides of the fence on that--rectifier tubes have an effect on sonics/rectifier tubes are not in the signal path & have no effect. My ears are not good enough for me to understand the differences and why I like something or don’t like something. In other words, I might be enjoying my SLP05 more than I ded before I put the Mullard in it, but I just don’t know why that is.

That might be a blessing or a curse, I haven’t figured out which.

@danager that's a really interesting piece 

that would be my first thing to try, if not just replacing the preamp, those are pretty soft and slow