Is upgrading stock tubes standard proceedure?


I'm just wondering if I'm the last guy to realize just how enormous an improvement can be had by upgrading stock tubes to NOS. Most of my system has been in place for some time now and I've sought to improve it's performance by tweaking. Tube changes have resulted in noticeable but subtle results; most of the time involving trade-offs... until now. I just upgraded the 6922s in my cj Premier 17LS to Amperex 6DJ8s with stunning results. I can't find any trade-offs, everything desirable in audio is improved IMHO. This is the kind of improvement I would have been looking for if I bought a new preamp and spent twice the money. As much as I've read about tube rolling, based on what I'm experiencing now, there isn't enough emphasis, especially by professional reviewers.

So, I guess my purpose in writing this thread is two fold:

1) Why don't tubes receive at least the same attention as the equipment they're in.

2) Just a heads-up in case there is anyone else out there who thinks they can't justify $100 or more for a small tube.
phaelon
An extra "H" got in that first URL. Here's a correction: (http://www.kraudioproducts.com/Kr/ProductMain.aspx?CatID=13)
I just place my order for these two tubes Mullard CV4004/12AX7 to be used in my VTL 7.5 preamp. I heard noting but good things about these tubes... I view purchasing NOS tubes like purchasing a rare wine some may like it and others may not.
many current-production tube components have circuits which are not tube sensitive. i have encountered many examples of this phenomenon. in such cases, replacing stock tubes is not beneficial.
Going from one tube to another does not guarantee an audibly detected change. The two tubes could have very similar sonic properties. Or the overall system is dimensionally flat to not allow for one tube's refinement to shine over the other.

If you go to the extreme and try for example, a premium Valvo or Amperex pinched waist tube, and compare it to something like Sovtek or Electro-Harmonix, even the most compromised tube design will show this difference instantly. The comparison may result in nearly the same tonality but dynamic contrasts, ambiance and decays of the NOS are significant compared to the newer manufactured tubes. And no, I am not talking about "warmth". The newer stock tubes also tend to sound forward and fatiguing (edgy) compared to the far more smooth and natural result of the NOS tubes.

If the signal passes through a tube, it WILL affect it's sound. There's no such thing as a tubed circuit that is not "tube sensitive", in this regard(the tube being the most "active" component in the circuit).
Agreed.
mcintosh claims that changing tubes will not change the sound of an amp or preamp. i can confirm that when i auditioned and reviewed the c220 preamp.

whatever differences existed were so small as to be insignificant.

the bat vk d5 cd player is another component which does not change its presentation when changing tubes.

the eastern electric mini max cd player is yet another component who's sound did not change when replacing the tubes.
I've owned a BAT VK-D5 for the past 6 years, and the sound has changed markedly(although it's never sounded disappointing) with various tubes I've had in it(no simultanious system changes)!! That's exactly why I won't have it upgraded to the SE version(no tube rolling possible). I've got six Siemens CCa's(NOS two years ago) in it right now, and it's never sounded as lucid, accurate, open and with as much bass definition, extension and slam as it has with them. A system has to be able to resolve the changes that will be manifested by a tube swap in whatever component, and your ears have to be able to recognize/appreciate the differences. I've heard other manufacturers make unreasonable claims to dissuade people from experimenting with designs that they think are flawless. Probably lest the owner find out it can be improved upon.