The Conrad Johnson PV-11 tube preamplifier is used primarily for its rich, best heard to date (other than the PV-9), tube Phono Stage. (I did not find an improvement in sound by routing my Kora Hermes DAC through the line stage which then fed into my Almarro 318B integrated amp). Steve Sank of Talking Dog Transducer Co, Tucson (35 years of tube experience/his father was in development with RCA) enhanced the sound of the PV-11 significantly with a few simple and needed mods which left the original design alone, yet added superior compnents - including replacing some factory Solen Caps (poor choice for a signal path) with higher quality and value Audiocap Theta capacitors and replaced one of the two ultra large black film caps in parallel off the transformer with a high value Nichicon electrolytic with great results (better bass, dynamics, soundstage, musical depth, midrange richness, more extended highs). This is pretty much the same change an ex well kown CJ employee makes also (except Steve Sanks is better).
I also owned an did an A-B in house with the CJ PV-5, PV-9a, PV-11, and PV-12. The PV-5 was warm to the point of sounding dull to me and the PV-12 started to tip the scale toward lean and solid state to me. The best sounding to me overall for both line and phono stage was the PV-9a until the mods went into the PV-11, which seemed to make the PV-11 phono stage sound every bit as dynamic as the PV-9a and perhaps slightly warmer in the mids (and in a much more compact enclosure). Both are great preamps, yet I felt the preamp in the 9a to be better. For using both line and phono stage as is, from listening and looking at the internal components, I feel that the PV-9a edged out the PV-11 with the exception that the phone stage in the PV-11 gave the PV-9a serious competition after the mods. I got a little bit of hum from the PV-11 phono stage though, until installing my dedicated line.
I know CJ used compression rings to ground the RCAs, and soldering them is a good very idea. Also, getting a three pin to two pin cheap adapter at ace will help you rule out a ground fault loop problem. Aside from removing the ground to ID the problem, you can shave off the edge of the wider prong on the adapter and try reversing polarity to see if that makes the problem go away.
BTW, I didn't like the look of the rack arms, so I simply took them off and replaced them with some hex button bolts as you can see in the photo. A Steve Sank of Talking Dog Transducer Co, Tucson (moscode expert and equipment repair and modifier extraordinaire) partially modified (as per my budget) Moscode Super IT gave the CJ a serious run for best phono with better dynamics, blacker background (less noise), and the ability to easily handle MC Carts. However, the CJ's ability to provide a slightly richer midrange (which my system needed a little more of) is why I chose the CJ phono stage over the Moscode Super IT. Something gained and something lost as usual. Be aware that original Moscode equipment often has dangerously undervalued caps in it.
An audiophile friend with years experience who heard both the CJ phono and modified Moscode Super IT bought the Moscode Super IT from me and loves it. Be aware that the original Moscode Super It had some dangerously borderline spec caps in it which were prone to fail and that a fully modified Moscode Super IT is supposed to be something to behold.
TUBES: Wonderful rich and warm yet extended sounding Mullard Long plates with square getters (12AT7, 12AU7, 12AX7 where applicable) ended up being chosen in all positions of the phono stage with the exception of a Sylvania "B" 12AX7 which substituted wonderfully (better than any other tube) in the 5751 spot. The sound had become overly warm and slightly dull with a Mullard also in the 5751 spot. However, the Sylvania 12AX7 "B" in the 5751 spot had great synergy with the Mullards and brought the sound back to life and expanded the soundstage. The Mullards have stellar mids which were also pushed nicely forward which I like. However, be forewarned that Mullard short plate 12AX7s don't sound all that good (almost all Telefunken and Mullard 12AT7 do sound good) and the great sounding Mullard 12AX7 long plates are prone to be microphonic and can be extremely expensive (return if microphonic). For those not already initiated to micro-phonic tubes, right after you receive and test them (leaving on in tube tester by themselves before installing them, put them in your tube tester for an hour before thesting, then install them in your system fully on and gently tap them to confirm that they are not micro-phonic. If one or more are microphonic, you will hear a ringing or tapping noise through your system. Sometimes just tapping the enclosure with the microphonic tube in it will do that. Also be aware, that a tube can test high in the first few minutes when you get it, and test bad 5 minutes later if it has a hidden defect. Sellers rarely give them more than a few minutes of use in their tube tester and don't really know if there are any hidden defects waiting to manifest for that reason. I recommend that you let the tube sit on in your tube tester for an hour and then retest to see if it still functions the same as it initially tested. If it reading is going down significantly, leave it in longer before accepting it as a tube to put in your system. There are a lot of substandard tubes being sold, and often because the seller doesn't have the time, knowledge, patience, or proper tester to test them properly. Also, higher testing tubes sound more detailed and leaner than older tubes. I suggest letting NOS tubes stay on in your equipment 24/7 for two weeks for proper break-in and better sound. In general, my favorite smaller tubes (12AU7, 12AX7, 6DJ8, etc) which were chosen for best combination of musicality warmth, and detail, are Telefunken and Mullard (I occasionally throw in a RCA or Sylvania for more warmth). I have found that in general the best tubes were usually made in the 40's, 50's, and early 60's.
Tubes that I have found to be both musical and detailed in order of most detail to warmer are: Amperex Holland & Siemens Telefunken Mullard Sylvania RCA Although many people love them, I personally found the Amperex & Siemens to be a little too detailed for my system and preference. I found Tung Sols to be detailed to the point of sounding dry and nervous to me so I left them off the list. Although both Mullard and Telefunken are my favorite brands of preamp tubes, I found Telefunkens to have a nice combination of detail and warmth, with the Mullards offering a smidge more warmth and slightly less detail. The Telefunken 6DJ8 seemed to be a tad more detailed than other Telefunkens however. I used Sylvanias in combination with RCAs sometimes, with the RCA being the warmest offering a rich and thick midrange, although sometimes lacking in the highs. In my PV-11, I liked to use a RCA 5751 and others to add more warmth. Although their tubes can be a little expensive and I occasionally do not agree with them, a great resource for tube information is Tubeworld on the internet.