Primaluna EVO 400 vs. stock Cary SLP-05 preamp?

I haven't heard either but reading the web pages I would stick with what you have if you're happy, I imagine the upgrade will even deliver more and it's made in the USA.

Decided on the SLP-05 Ultimate Upgrade. The preamp is on its way to Cary.
 In its place I’m using a Formula 1 modified Cary SLP-98P.  To my ears, the mod’d 98P sounds better than the stock SLP-05. I’ll report on the mod’d 05 after I receive it.

Good choice imo.

I also vote for the SLP-05.  I owned the 05 as well as the 98 and the o5 was significantly better in my experience.  The fact that your modded 98 was better than a stock 05 is very impressive!  I'm curious to see how the upgraded 05 stacks up.

Curious to see what you think about the upgrade. 
I, too, had the 98, then F1 98, then 05.  
I also considered the ultimate upgrade, but ended up switching to a different preamp. 

Let us know what happens with the upgrade. 

The Cary Audio SLP-05 Ultimate Upgrade is complete. Haven’t done extensive listening yet, but initial impressions are very good. It’s at least as good as the Formula 1 SLP-98p, and seems better in some regards. Very tight bass, providing a good foundation fot the music. Great imaging. Very sweet vocals.
Worth the money to me. If you can afford the preamp, go for the upgrade.
BTW, Cary has significant sale prices on both preamps.

@cakids Have you compared the Cary linestage to any other premaps (such as arc ref6, vac renissance mk v etc)?

Sorry. My previous preamps were all pretty vintage. ARC SP6, CJ PV-7 and others. Currently using integrateds in another system. Absolutely love the Manley Stingray II, but it’s hard to compare to the Cary, since the room and other components are so different.
I would consider the PL Evo 400 or the Zesto preamps if I were buying now. Heard them both at dealers, and was very impressed.

"...Have you compared the Cary linestage to any other premaps (such as arc ref6, vac renissance mk v etc)?..."

I have a Cary SLP98 F1 and a couple of Audio Research pre amps. The AR preamps were a bit dryer than the Cary. It would depend on your system and likes to which you would prefer.