Question for tube aficionados

I have a vintage Conrad-Johnson PV 11 preamp.
 I’ve always re-tubed it  with the cheapest tubes from Tube Depot (e.g. Electro-Harmonix 12AU7 and 12AX7, Sovtek 5751 and the like.). I’ve been very happy with the sound.
 My question is:
 Would it be worthwhile to spend more money on more exotic tubes?
  Would there be any appreciable difference in the sound?
 I’m powering the system with NuForce Reference 9 V3 monoblocks.
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Right now, I’m very happy with my NuForce Reference 9 V3’s.
And they’re a few thousand less than the Bel Canto.
 I know there is extreme predjudice against class D.
But you have to hear the NuForce to render an informed opinion
Telefunkens and Amperex are no better than new tubes like the psvanes... has anyone compared all three side by side?

I haven't tried the Psvane, but according to forum members it is a premium quality new production tube at a premium price. 
A 6SN7 costs as much as a high quality NOS tube.

Looking forward to the answers to your question.

I have some experience with the 12AX7 from Psvane. I would definitely give them the nod over all current production tubes that I've tried, except the Gold Lion. The GL gets the nod for tighter, more tuneful bass.

I would not put either brand ahead of a quality, tested, NOS Mullard, Amperex Bugle Boy, Siemens, or Telefunken in sound quality. As with all things audio related, this is a subjective statement. There are other NOS than can be quite good, of course, but those are the biggies. They all have a sometimes subtle, but definite and unique sound character. The different brands will excel in different equipment and systems, and based on listener preference, of course.

I'm not surprised that you are digging the Amperex tubes, as that is one heck of a 12AX7... plenty of detail and the tube black magic, and a nice match with a neutral-to-cool sounding amp. If still running the Belles, I would expect many to lean toward the Siemens or Telefunken. All just generalizations and personal preferences on my part, of course. 

If you can afford to keep both, do it. You may decide to make a power amp change down the road, and those NOS Telefunken tubes could come in handy... they're not going to go down in cost in the future. I could kick myself when I think of the NOS tubes I've sold along with gear over the years.
Well, I’ve done a lot of listening lately, and on my system, the Telefunken tubes work better than the Amperex. They are just cleaner and more elegant.
 I’m sure the Amperex are great tubes, but they don’t work as well with my setup.
 It’s possible if I gave them more break-in time they would sound better.  But I don’t want to suffer through that period when I can enjoy my system right now
So you like the Tele's, they're excellent tubes. You gave the Amperex a chance, as long as you burned them in for 60 hours and then did some critical listening.
So that's the problem with tube rolling, they sound different and depending on your tastes and your system they may or may not work for you. I found the Telefunkens to be pretty good, I liked them more than some Amprex tubes, including Bugle boys. As you wrote, they are great tubes, but just not in your setup. If you are already used to and like the sound of the EH, I think you might want something that hits with a little more punch than the tele or amprex tubes, I would try the new Golden Lions or the psvane, if you want to try NOS I would recommend you look at some RCA blackplates from the 50's or early 60's. I've tube rolled a lot of different tubes, and it's always a give and take with tubes. Amprex gets such a good rep because they are very balanced, but that might not be what you are looking for, and you don't really understand that until you try them out for yourself. Happy hunting
I am actually delighted with my system right now. My search is over.
 The Telefunkens are my tubes of choice.
The current production Gold Lions produce a sound that comes closer to the old production Philips tubes such as Mullard and even the less rich sounding Amperex.  Still many of the old 5751s while excellent in regard to tone are even better for imaging and sound spectrum profile balance  i.e. relative amounts treble to mid to bass that is partly a function of what a tube type can alter sort of a tone matter but different in my mind.  Gold lion does not make a 5751 to my knowledge but I sure would like to see them try. They do make a 12AU7.
There has been a run on whether a 6SN7 can be subbed for a dual triode 9 pin minature, and it can in some applications take the place of a 12AU7 in some applications. adapters can be bought on Ebay and elsewhere.  I am not sure whether you pre would allow the diferences betwen the 2 or not, but my understanding is that they serve similar purposes.  6SN7s are said to be very linearand there are plenty of 12AU7 bashers around on tube froums.
I owned the PV5, PV8, PV11 and PV12 over the years. Going from memory, seems the later versions starved the tubes a bit. before you start serious tube rolling, may want to measure the plate and cathode voltages and see what there are, then calculate the current going through the tube. On my PV12, there was less than a milliamp, so changed out the plate and cathode resistors to at least get the current up to a milliamp. sounded much more open and less constrained.

The PV5 I wish I had never sold...did not have the highest resolution, but was such a musical sounding piece.

If the CJ uses any 12AU7's try NOS RCA 5963. These are always a serious upgrade from your new stock 12au7's and they're a plug and play replacement. Highly recommended.
And almarg has stated an important point about the use of the 5751 variant in your CJ preamp...
Please note: The indiscriminate substitution of type 12AX7 tubes for the 5751 will seriously degrade the sonic performance of the unit.

The 5751 has lower gain, so it's recommended to stay with a 12AX7.

This comment is backward. The book is saying not NOT to replace the 5751 with 12ax7. The higher gain of the 12ax7 would overdrive the circuit, being 30% higher. That’s why it says not to indiscriminately do that.  
I have a used the PsVane with much sucess.
I have an Amp that uses the 12AX7 In that I have put Sovteks (Basically nothing more than a tube to put in a tube socket) 
Also put in Vintage Mullards and Tele's . The matched Set Psvane to me sounded better balanced, clearer and detailed.
The Mullards a little bright & the Tele's A little to creamy for my system.
 But it is always specific to equipment.
I also had a tube phono section which required both pairs. Again I tube rolled the Sovteks and
only replaced with the PsVanes. Vintage is great but they have their issues.  With the PsVanes were very quite and for the price worked great and you should have no regrets. At worst they become a very good back up set just in case your vintage choice go south. But now my vintage 12AX&'s are my back up and the Psvane are still in and working fine for well over 2 years.
Lastly give them a little time to break in. Out of the box you will know you are the right path.

I have Shughang Black Treasure 12AX7LS and they are mostly better than Telefunkens. Tighter, cleaner bass, clean bright sound without glare and sweet highs. Slightly reduced air.