how important is linestage preamp with vinyls only

I think I would at the least try a few more 12ax7 tubes,or even better try some Sylvania 5751 3 mica black plates in your current CJ preamp and see how much more performance you can squeeze out ..This may be enough for you to keep what you have and save some money for more Vinyl....

The pre-amp's line stage is important and its presence is audible and influential on the signal it receives either from a phono stage (or an outboard phono stage) CDP, what ever. If your phono stage has tubes and your line stage has tubes then you have 2 opportunities to dial in the tone you want. Some times just the tube in the phono stage will do it, some times just the line stage, more often than not both. Operating on the assumption (I do not know about the PV12) I would start by selecting a tube for the line stage that has a general reputation for being neutral in tone, quiet, and rugged. Then I would try to find a tube that produced the tone you want from the cartridge you are using. It is not always easy to get this right so take your time.

A good place to start is to tell folks what kind of cartridge you are using now, what kind of tone you are getting, and what you would like to improve. Also indicate what tube you are using in the line stage and what tone it is producing as it relates to any source you use. With that info I'm sure there are some folks who can give you some specific and knowledgeable advise.

The linestage provides two functions, if you are using an outboard phono stage. It adds gain. If the output of your phono stage is inadequate to drive your amplifier, that gain is needed. And it adds an attenuator in the signal path and possibly bass/treble/balance controls if you want to use such. Both the gain function and the control functions can also color the sound, for good or ill. If your phono stage has a robust output with the cartridge that is driving it, and if it has a volume control, there is no need for a formal linestage at all.

(There is a third issue with impedance matching; the phono stage has to have a low enough output impedance to drive the cables between it and the amplifier inputs, in order to do away with the linestage.)

If your question is whether or not to switch from a full function preamp (meaning a preamp with built-in phono) to separate phono and linestages, I would say that it is impossible to say, since only you can determine what pleases you most. But separate boxes will cost more, require another interconnect pair, etc. Rollling tubes may help, but what are you trying to achieve? Changing capacitors in the signal path would likely help even more than rolling 12AX7s in the CJ.

If you plan to use stand-alone phonostage with volume control like EAR834, it'll keep you with tube business and you won't need preamp.

Thank you everybody.
To Thorman – yes, you are exactly right about trying different tubes. The thing is I was almost at the point to buy some tubes (good ones) from Brent Jesse, $300-500 range per matched pair. I looked at other places as well. Should I mention that I started from ground zero exactly a year ago. So at the time I just needed to start somewhere and I bought the PV12 (this has 12AX7, 5751 and 12AU7) which didn't fail me yet.
But while speaking with Brent it crossed my mind that not all pre-amps (and I intended to stay within CJ for time being, but even with those) have the same tubes – some have 6922, some 6H30P and so forth. This and the fact that good tubes are costly made me consider the upgrade first, as well as a minor fact that the PV-12 doesn’t have the remote.
And certainly, regarding the question on what I am looking for – it is hard for me to realize the deficiency of the sound until I hear something else. I am quite happy with the PV12 sound as it is now. I should add – provided the record quality is sufficient/high enough. On some records violins are too harsh, on some bass is not too expressive, but since I have a few records which sound very good I assigned the above week points to the record rather then to the device. But on the other hand I thought I should rather go a little higher, get myself a (as they say) better (read – more pricey) CJ device, run it at my place with all the arms and cartridges that I have and then decide. But you are right – one needs money for the vinyl J
To Newbee – on the cartridges side – I have a few, I have not decided though which one (or ones) I will keep. I have Grado Reference (Old Stock), Grado Amber the Tribute, Ortofon Windfeld, Acutex M320 and VDH Colibri LWG. “Only” 2 arms so far – the Rega 300 that came with the used TT (Oracle Paris, old model) and Sumiko MDC800. I am planning to get a light weight (may be some used SME) for my high compliance Colibri, as well I am considering a used RS-212D for Windfeld. Yes, I like music more than HIFI but I don’t mind having some fun with different setups as long as I don’t take the next mortgage.
Speaking about the tone – I would say balancing the details and the ‘warmth’ I will go for the latter maintaining enough details as much as I can.
To Lewm – good point about the controls on the phono stage, I didn’t think about it that way! I was missing tone controls on the pre-amp initially when I started but now I don’t think I miss that part too much. I also spoke with Ed from CJ about changing the capacitors in the PV12 but it doesn’t look like they do such an upgrade in PV12. They do that on the PR16 amp (and EV1 phone stage) though. And this was another reason for my question as well.
But overall it looks like I have more defined plan now thanks to you folks.
Regards