Conrad Johnson Preamplifier & Tubes Linn Turntable
I have a Almarro 318B amplifier, and a Linn Basik turntable with Basik LVX tonarm and Zu Audio Druid Speakers and use Acoustic Zen Wow Interconnects and Zen El Nino power cords (I like the El Nino better than the Tsunami, except into my amp where I use a somewhat warmish Tsunami power cord) . I have owned or had in my home a Conrad Johnson PV-5, PV-9, PV-11, and PV-12 preamplifiers which I used mainly for their phono sections.
The PV-11 and PV-9 came in as very close in sound. I felt the PV-9 to be slightly better than the pv-11 for having a little more dynamics until Steve Sank of Talking Dog Transducer Co in Tucson swapped out two black Solen produced caps in the Phono section signal path for some 3 UF Audiocap PPT Theta Capacitors (one factory cap had to go under the board for it to fit). He also put in some quality soft recovery diodes and took out one of the large black film caps by the transformer and put in one large Nichicon Elecrolytic (leaving one film in place) and also put in a nice IEC so I can use a good power cord instead of the very cheesy original CJ stock power cord. I also took opportunity at the time to take the funky looking rack arms out and replace them with some nice round top black hex nuts from Ace Hardware, typical of those used on some Audio Research equipment.
BTW, the PV-5 sounded too warm to the point of being dull to me and the PV-12 seemed as if it was starting to sound a little too solid state for me (although still very nice and tubey). I have heard that the PV 10a is not so hot, but have not listened to it at all.
That upgrade mods mentioned transformed the PV-11 by my ears to sound better than the PV-9. The slightly fuzzy recessed relative sound of the PV-11 became slightly richer and more dynamic to me than the PV-9, and in a more compact package.
My favorite tubes in the PV-11 phono stage are two Mullard Long Plate 12AX7 tubes at the back, a GE 5751 (a little more detailed yet still warm likes its RCA 5751 twin), and at the front, a Mullard 12AU7 long plate.
Runner up for the 12AX7 tubes were Telefunken 12AX7 tubes which sounded slightly more detailed and slightly less warm in my system than the Telefunken yet still very nice. I tried a Mullard 12AX7 in replacement of the GE (RCA) 5751 and the sound of the phono stage became much more detailed and dynamic. However, on balance, I preferred the sound of the more relaxed GE or RCA 5751.
At the very back I settled on a Mullard 12AU7 long plate. (some times a Mullard or Telefunken 12AT7 can sound better than a 12AU7 although that did not work well for me in the phono (the 12AT7 is better sounding substitute than the 12AU7 same brand in the tube output stage of my Kora Hermes DAC though).
The Mullard long plates by the way are those with square getters produced from 1957 or earlier.
Bear in mind that I have a quick dynamic and somewhat detailed yet still warm system, so what I prefer is put into place to balance the net sound for my system. Other configurations of tubes may work better in other systems.
However, I found I interestingly have gone against the flow of mass opinion and preferred the warm and rich sounding budget priced Linn Basik Turntable (slightly tubby bass run runs nicely up into a rich lush midbass) to the more detailed and sophisticated Linn Sondek LP 12 which I A-B'd in my home. The Linn Sondek was more detailed but not as warm. It seems the steel top on the Sondek turntable compared to the wooden compressed board of the Basik turntable brought out detail and lost warmth. I also personally preferred the sound of Linn Basik LVX tonearm with its non-mind messing detachable headshell for installing cartridges on the Basik turntable to the Akito tonearm (which I also did an A-B with in my home, the Shure V15 V cart with VN5MR stylus sounds best in this system to me than many other carts I tried).
I suspect people with warmer speakers and amps may well prefer a different pre-amp and turntable configuration. Synergy and where the owner wants the sound to go as well as personal preference may change all of the above.
By the way, I found the line stage of the PV-11 to sound very nice, although seemingly not quit as capable as the phono stage which sounds better to me through the record out (which bypasses the line stage allowing me to put junk tubes in there now).