Primaluna Prologue 4 tube upgrades

I recently acquired this amp and at first thought it was sounded great, but was not completely happy with the LF response with my modest Dali Zensor 1 monitor speakers and nicely upgraded Dared SL2000a amp. So, I swapped some Siemens 12AX7 and 12AU7 tubes into the unit for the stock Chinese tubes and holy hell, this amps is really quite fine! It has great control of the LF now and I realize that a veil of grunge I was hearing has vanished! I might swap some better power tubes in for the stock PL (Chinese) EL34's to see if that improves it even more. Or roll some Gold Lion KT88's into it. The amp has the unique feature of auto-biasing the tubes, which was always a hassle with my HK Citation I and V amps . Honestly, I have been thinking about upgrading to PL's high end integrated amp, but from what I hearing today, I might just stay with this set up. BTW, I have had a long series of far more expensive monitors in my system, yet these Dali Zensor 1's are the best I have had. They are thoroughly musical.
I think there is an active community of people who have rolled tubes in the Prima Luna amps, and I am surprised no one has responded to you thus far. I really like the Gold Lion (Ru.) KT-88s and think you will like them as well. It can't hurt to get the advice of Mr. Deal on the matter, but I know he has advocated for them in the past.
I'm an EL-34 fan myself, and own an EL-34 only amp, and I would say check out the Gold Lion KT-77 this EL-34 variant to me was a huge upgrade in my amp over the likes of JJ, EH, etc. A very worthwhile upgrade and inexpensive as tubes go. This will likely give you a bit warmer sound than the KT-88 though I haven't heard your amp specifically.
I like these EL34s: RFT Siemens, Shuguang Black Treasure (best in my system), SED Winged C, Reflektor 6n3ce(6L6).
I have tried many different tube combinations and settled on the Amperex/Holland 12AU7's and Shuguang Black Treasure 6CA7's . Good extension at both ends , warm presentation , clarity with musicality and definition .
The Primaluna El-34's are a pretty nice tube in their own right . My second best favorite small tube is the RCA Blackplate ( I think that this is the correct name) 12AU7 .
For a little less money , this combination is quite nice also .

Caveat ... I am using the Primaluna Dialogue Premium Integrated amp . I don't think that there will be much difference between these amps concerning tube choices . I have owned the Prologue integrated as a reference .

Good Luck
Correction to my above post... instead of Amperex/Holland 12AU7's , I should have said 7316's . These are a direct replacement for the 12AU7's . Really a very nice tube .

Too bad we can't do corrections to already posted threads here .
The 7316 is a direct sub for the 12AU7, ECC82 etc, pre amp tube. It is selected for low noise and high reliability and has been made with more than one architecture. The were intended for fine instrument and computer use. They are, if real, my strongest favorite sub for the 12AU7. You are more likely to get a real one always Heerlen Amperex with Ct# date code for late 50s and early 60s with a computer company logo like Hewlett Packard.
So you ask what's the tube sound like? It is a tube that is capable of crystalline highs without being piercing and creates an almost surreal technicolor three dimension soundstage, pure mids and again very dramatic frequency range digging into the bass- and getting out a clean non muddy bass. Beyond that I just like the way they sound.
If you get a 7316 that sounds like crap it either isn't a true 7316 or is well past it's prime, keep hunting. Unfortunately there are some dishonest or ignorant sellers who are giving their better 12AU7s the 7316 name. Make sure there is the right triangle acid etch indicating Heerlen Holland. That alone separates much wheat from chaff. If all else falls write me privately.
I have the Primaluna HP Integrated and wondering about changing out the tubes. Would it be best to change out power tubes or preamp tubes first? Looking to increase clarity, imaging, and soundstage extension but I don't want to lose the midrange warmth I get from the EL34's. Thinking about KT120s or some NOS tubes for the 12au7's. Any recommendations would be appreciated. Being there are 8 power tubes and 6 12au7's, it could be pretty expensive to experiment with tube rolling. Any advice?
Djfst ;
My experience with KT 120's showed a lack of midrange .
Their strength was in the upper & lower ranges.

Keep your 34's and try RCA clear top 12AU7's . Just use 4 in the two front positions on each side and keep the Primalunas in the rear position on each side . I found the Primaluna 12AU7 to be a rather neutral sounding tube .

Good luck
Thanks for the suggestion, Saki70. Looked up those RCA Cleartop's and they could be just what I need. And they are a really low price considering some other NOS tube prices. Excellent suggestion and well worth a try, especially in the preamp section of my Primaluna Integrated.